CN116159878A - Device and process method for preparing high-performance fine-grain weak-texture magnesium alloy by multidirectional dynamic torsion extrusion - Google Patents

Device and process method for preparing high-performance fine-grain weak-texture magnesium alloy by multidirectional dynamic torsion extrusion Download PDF

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Publication number
CN116159878A
CN116159878A CN202211570745.2A CN202211570745A CN116159878A CN 116159878 A CN116159878 A CN 116159878A CN 202211570745 A CN202211570745 A CN 202211570745A CN 116159878 A CN116159878 A CN 116159878A
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torsion
magnesium alloy
extrusion
rod
torsion extrusion
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王利飞
白云丽
成颜辉
张强
郑留伟
程伟丽
王红霞
江树勇
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Taiyuan University of Technology
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Taiyuan University of Technology
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C23/00—Extruding metal; Impact extrusion
    • B21C23/02—Making uncoated products
    • B21C23/04—Making uncoated products by direct extrusion
    • B21C23/08—Making wire, bars, tubes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C23/00—Extruding metal; Impact extrusion
    • B21C23/32—Lubrication of metal being extruded or of dies, or the like, e.g. physical state of lubricant, location where lubricant is applied
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C25/00—Profiling tools for metal extruding
    • B21C25/02—Dies
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C25/00—Profiling tools for metal extruding
    • B21C25/08—Dies or mandrels with section variable during extruding, e.g. for making tapered work; Controlling variation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C26/00—Rams or plungers; Discs therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C31/00—Control devices, e.g. for regulating the pressing speed or temperature of metal; Measuring devices, e.g. for temperature of metal, combined with or specially adapted for use in connection with extrusion presses

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  • Mechanical Engineering (AREA)
  • Extrusion Of Metal (AREA)

Abstract

The invention belongs to the technical field of plastic forming of light metal, and particularly relates to a device and a process method for preparing high-performance fine-grain weak texture magnesium alloy by multidirectional dynamic torsion extrusion. According to the invention, dynamic torsion extrusion is respectively carried out on the magnesium alloy blank at different advancing speeds and different torsion angle speeds through the dynamic torsion extrusion rods at the left side and the right side, and meanwhile, the screw thread male die drives the blank to twist forward, so that the c-axis of the magnesium alloy blank is forced to deflect, and grains are refined. Meanwhile, asymmetric grooves are formed in the front end portions of the torsion extrusion rods on the left side and the right side, plastic deformation of magnesium alloy blanks is increased, texture refinement grains are weakened, meanwhile, the torsion directions of the torsion extrusion rods on the left side and the right side and the torsion directions of the thread male dies on the upper portion are opposite, and the directions on the left side of the contact are the same, so that friction forces on the two sides are different, deformation of magnesium alloy is increased, and the purpose of weakening the texture refinement grains is achieved. Finally, the blank is further extruded through an extrusion area to achieve the required magnesium alloy bar with uniform structure.

Description

Device and process method for preparing high-performance fine-grain weak-texture magnesium alloy by multidirectional dynamic torsion extrusion
Technical Field
The invention belongs to the technical field of plastic forming of light metal, and particularly relates to a device and a process method for preparing high-performance fine-grain weak texture magnesium alloy by multidirectional dynamic torsion extrusion.
Background
The magnesium alloy is the structural material with the minimum density in the current metal, has the advantages of high specific strength and specific rigidity, good thermoformability, easy recovery and the like, thus the magnesium alloy plays an important role in the fields of automobiles, 3C, aerospace, military and the like, and is more praised as a green energy material in the 21 st century. However, the crystal structure of the magnesium alloy is in a close-packed hexagonal shape, only two sliding systems are easy to start at room temperature, and the number of the sliding systems is less than five independent sliding systems required by deformation of polycrystal, so that the magnesium alloy is difficult to plastically process at room temperature, and macroscopic performance is poor at room temperature mechanical property. In addition, because the critical shear stress difference between the basal plane and the non-basal plane of the magnesium alloy is larger, the non-basal plane slip is not easy to start during low-temperature deformation, so that the grains in the deformed material have preferred orientation to form a strong basal plane texture, the subsequent deformation is not facilitated, and the application of the magnesium alloy in various fields is limited. Grain refinement can significantly improve various mechanical properties of the metal material, as can magnesium alloys. The severe plastic deformation technique has been demonstrated to be effective in refining magnesium alloy grains such as High Pressure Torsion (HPT), multi-directional forging (MDF), equal channel angular Extrusion (ECAP), rotary extrusion (TE), which can extremely refine grains and even obtain ultra-fine grain structure. However, torsional deformation is generally complex, the die processing requirement and equipment requirement are high, the die is required to bear large pressure, the torsion degree of the material is low, and the die has great limitation on realizing continuous preparation in a large scale.
Therefore, the invention provides a device and a method for effectively weakening deformation texture and refining grains of magnesium alloy, which are very important for expanding the application range of the magnesium alloy.
Disclosure of Invention
The invention aims to solve the problems and provides a device and a process method for preparing high-performance fine-grain weak texture magnesium alloy by multidirectional dynamic torsion extrusion. By the device and the processing method thereof, continuous and severe torsional extrusion deformation is generated on the magnesium alloy blank in the processing process, and the c-axis of the magnesium alloy is deflected, so that the weakening texture and the grain refinement are realized, the room temperature mechanical property of the magnesium alloy is improved, and the application range of the magnesium alloy is enlarged.
The invention is realized by the following technical scheme: the utility model provides a diversified device of little texture magnesium alloy of fine grain of dynamic torsion extrusion preparation high performance, includes vertical extruder, upper portion twists reverse extrusion mould, left side twists reverse extrusion mould, right side twists reverse extrusion mould, outside die carrier and power device, wherein:
the vertical extruder comprises a movable cross beam, two upright posts and a working platform; the two stand columns are vertically upwards arranged above the working platform, and the movable cross beam spans over the stand columns and can move up and down along the stand columns;
The upper torsion extrusion die comprises a threaded male die fixing plate, a first bearing, a threaded male die and a first threaded pipe, wherein the threaded male die fixing plate is arranged below the movable cross beam, the first bearing is axially and vertically arranged below the threaded male die fixing plate and is assembled with the threaded male die, the threaded male die is sleeved with the first threaded pipe meshed with the first threaded pipe, and the first threaded pipe is fixed on a stand column on the right side of the extruder through a fourth supporting rod;
the left side torsion extrusion die comprises a left side torsion extrusion rod, a second threaded pipe, a universal ball, a connecting rod and a wheel disc; the wheel disc is rotatably supported on a left upright post through a first supporting rod, the left end of a connecting rod is hinged to the edge of the wheel disc and rotates together with the wheel disc, the right end of the connecting rod is connected with a universal ball, the universal ball is arranged at the top of a left torsion extrusion rod, a second threaded pipe is fixed on the left upright post through a second supporting rod, the upper half part of the left torsion extrusion rod is a threaded rod matched with the second threaded pipe, the cross section area of the lower half part is gradually reduced, a left groove is formed, the wheel disc is driven to rotate through a first motor, and then the connecting rod is driven to rotate, and the connecting rod drives the left torsion extrusion rod to twist and advance under the condition of being matched with the threaded pipe;
The right-side torsion extrusion die comprises a right-side torsion extrusion rod, a second bearing, a positioning sleeve, a power sleeve and a threaded rod; the right side torsion extrusion die is fixed on a stand column on the right side of the extruder through a third support rod, wherein a threaded rod penetrates through the inside of a positioning sleeve, a power sleeve and a torsion extrusion rod, the positioning sleeve is fixed on the threaded rod through a bearing, the threaded rod can rotate freely, the power sleeve is embedded in the inside of the positioning sleeve, the circumferential fixation with the positioning sleeve is realized through edge slotting and is limited by the length of the positioning sleeve, the threaded rod is in threaded connection with the power sleeve, a second bearing is arranged in the power sleeve, the second bearing is matched with the right side torsion extrusion rod, the upper half part of the right side torsion extrusion rod is hollow, the inner surface of the right side torsion extrusion rod is provided with a protruding part which is axially parallel with the right side torsion extrusion rod, the protruding part of the right side torsion extrusion rod is embedded with the groove of the threaded rod, the lower half part of the right side torsion extrusion rod is a solid rod with a right groove, the right groove is gradually reduced in cross section, and the left groove part of the right side torsion extrusion rod is asymmetric;
The external die carrier is arranged on a base plate fixed above the working platform and comprises a front module and a rear module; the front module and the rear module are fixed through bolts, an extrusion space is formed in the rear module, and the extrusion space comprises a vertical middle channel and left and right channels which are formed on the left side and the right side of the rear module and communicated with the bottom of the middle channel and are obliquely arranged; the working platform and the backing plate are provided with a material leakage hole which is communicated with the middle channel and has an inner diameter smaller than that of the middle channel; the threaded male die extends into the middle channel from top to bottom, and the left side torsion extrusion rod and the right side torsion extrusion rod extend into the left channel and the right channel respectively; the middle channel, the left channel and the right channel together with the material leakage holes form a torsion extrusion channel; the front module and the rear module are internally provided with heating channels for the flow of the organic heat carrier;
the power mechanism is a first motor and a second motor (both motors capable of rotating bidirectionally) for driving the left torsion extrusion die and the right torsion extrusion die; the first motor drives the wheel disc to rotate, and the second motor drives the threaded rod to rotate.
The torsion extrusion channel is sequentially provided with a torsion pushing area, a dynamic torsion extrusion area and an extrusion area from top to bottom. The magnesium alloy blank is continuously twisted and advanced under the drive of the threaded male die in the twisting pushing area, the magnesium alloy blank reaches the dynamic twisting extrusion area, dynamic twisting extrusion with different advancing speeds and different twisting angle speeds is respectively carried out through dynamic twisting extrusion rods on the left side and the right side, and meanwhile, the threaded male die drives the blank to twist and advance, so that the c-axis of the magnesium alloy blank is forced to deflect, and grains are refined. Meanwhile, asymmetric grooves are formed in the front end portions of the torsion extrusion rods on the left side and the right side, plastic deformation of magnesium alloy blanks is increased, texture refinement grains are weakened, meanwhile, the torsion directions of the torsion extrusion rods on the left side and the right side and the torsion directions of the thread male dies on the upper portion are opposite, and the directions on the left side of the contact are the same, so that friction forces on the two sides are different, deformation of magnesium alloy is further increased, and the purpose of refinement grains is achieved. Finally, the magnesium alloy blank is extruded to obtain the required high-performance magnesium alloy bar. The device can realize the preparation of high-performance fine-grain weak texture magnesium alloy through multidirectional dynamic torsion extrusion deformation.
Further, the front module, the rear module, the left side torsion extrusion rod, the right side torsion extrusion rod and the thread male die are all made of 4Cr5MoSiV1 hot work die steel.
Further, the surface roughness of the left torsion extrusion rod is Ra0.08-0.16 mu m, the surface roughness of the right torsion extrusion rod is Ra0.16-0.4 mu m, and the surface roughness of the rear module torsion extrusion channel is Ra0.4-0.8 mu m. The torsional extrusion channel and the roughness of the left torsional extrusion rod and the right torsional extrusion rod form asymmetric distribution, so that the difference value is formed between the extrusion process and the friction force generated by the blank, the differential flow of the blank is further promoted, and shearing extrusion deformation is generated to weaken the basal plane texture of the blank.
Further, when the preparation of the magnesium alloy bar is finished, the vertical extruder moves upwards, the threaded male die is controlled to reversely rotate to withdraw from the channel, and the torsion extrusion rods on the left side and the right side are also controlled by the motor to withdraw from the channels on the left side and the right side, so that the preparation is made for the next bar extrusion.
A process method for preparing a high-performance fine-grain weak texture magnesium alloy bar by multidirectional dynamic torsion extrusion comprises the following steps:
s1, magnesium alloy blank pretreatment:
s1-1, processing a magnesium alloy blank into a cylindrical magnesium alloy bar, polishing the surface of the magnesium alloy bar by using 600-mesh sand paper to remove greasy dirt, and sequentially polishing by using 800-mesh, 1000-mesh and 1200-mesh sand paper until the surface of the magnesium alloy bar is smooth;
S1-2, mixing acetone and absolute ethyl alcohol in a cleaning tank according to a volume ratio of 3:2, and uniformly stirring to prepare cleaning liquid;
s1-3, immersing the magnesium alloy bar stock prepared in the step S1-1 into the cleaning liquid prepared in the step S1-2, placing the cleaning tank on an ultrasonic cleaner to ultrasonically clean the magnesium alloy bar stock for 60min, then taking out the magnesium alloy bar stock, cleaning the magnesium alloy bar stock with absolute ethyl alcohol, and finally drying the magnesium alloy bar stock by a blower;
s1-4, coating graphite oil solution on the surface of the magnesium alloy bar prepared in the step S1-3, and reserving for later use;
s2, preheating the magnesium alloy bar stock: setting the heating temperature of a vacuum atmosphere heating furnace to be 450 ℃, and after the heating furnace temperature reaches the set temperature, placing the magnesium alloy bar into the heating furnace, and preserving the heat for 3 hours;
s3, lubrication, assembly and preheating of the dynamic torsional extrusion deformation forming device:
s3-1, lubrication: smearing graphite oil solution on the surfaces of the thread male die, the left side torsion extrusion rod, the right side torsion extrusion rod, the power sleeve, the contact part between the positioning sleeve and the second bearing and the right side torsion extrusion rod and the inner surface of the torsion extrusion channel;
s3-2, assembling:
firstly, installing and fixing a backing plate on a working platform of a vertical extruder, installing a rear module and a front module together by four bolts and fixing the backing plate, then assembling and introducing a left torsion extrusion rod into a left channel of the rear module and matching with a second threaded pipe, connecting a connecting rod and a wheel disc through a universal ball on the upper part of the left torsion extrusion rod, penetrating a threaded rod in a right torsion extrusion die into a positioning sleeve, a power sleeve and the right torsion extrusion rod, installing the power sleeve and the right torsion extrusion rod, fixing the positioning sleeve and the power sleeve in the circumferential direction, enabling the power sleeve to move up and down along the edge of the positioning sleeve, matching the power sleeve with a second bearing and the torsion extrusion rod, assembling and introducing the right torsion extrusion rod into a right channel, and aligning the position of a discharge hole with a leakage hole penetrating the working platform and the backing plate;
S3-3, preheating: controlling the temperature of a medium in the heating channel to be 300-500 ℃, and preserving heat for 2-4 hours after the temperature reaches the set temperature for later use;
s4, multidirectional dynamic torsion extrusion forming: the middle channel, the left channel and the right channel together with the material leakage holes form a torsion extrusion channel; the torsion extrusion channel comprises a torsion pushing area I, a dynamic torsion extrusion area II and an extrusion area III which are arranged from top to bottom;
s4-1, withdrawing the thread male die from the torsion extrusion channel, filling the magnesium alloy bar stock in the torsion pushing area I, and pushing the thread male die into the torsion extrusion channel; operating the vertical extruder, pushing the threaded male die downwards, driving the magnesium alloy bar to rotate and push downwards; when the magnesium alloy bar reaches a dynamic torsion extrusion area II, the first motor on the left side drives the wheel disc to rotate, the wheel disc drives the connecting rod to rotate, the left torsion extrusion rod is further pushed to twist forward to extrude the blank, the second motor on the right side drives the threaded rod to rotate, the power sleeve is driven to move forward, and meanwhile the right torsion extrusion rod is driven to rotate and move forward, and the magnesium alloy bar is extruded; in the process, the magnesium alloy bar is driven to twist along with the threaded male die at the top, so that the magnesium alloy bar is spirally advanced in the left-right asymmetric spiral extrusion process, the c-axis of the magnesium alloy bar is deflected, and the weakened texture and crystal grains are further refined; when the bar reaches the extrusion area III, the bar is further extruded to reach the required magnesium alloy bar with uniform structure; in the process of torsion extrusion forming, controlling the temperature of a medium in a heating channel to be 300-500 ℃;
S4-2, taking out the magnesium alloy bar prepared in the step S4-1, polishing the surface of the magnesium alloy bar by using sand paper, cleaning the magnesium alloy bar by using the cleaning liquid prepared in the step S1-2, and finally, secondarily cleaning by using absolute ethyl alcohol, and drying by using a blower to prepare the fine-grain weak-texture high-performance magnesium alloy bar capable of being directly put into use.
Compared with the prior art, the invention has the beneficial effects that:
1. the torsion extrusion channel provides intense spiral torsion deformation and dynamic recrystallization, so that the basal plane texture of the magnesium alloy is effectively weakened, and the mechanical property of the magnesium alloy is improved;
2. the extrusion speed of the left and right torsion extrusion rods and the angular speed of torsion are adjustable, the small asymmetric grooves are formed in the left and right torsion extrusion rods, and the torsion directions of the torsion extrusion rods on the left and right sides and the upper thread male die are adjustable, so that friction forces on the two sides of a contact part are different, the blank is further subjected to spiral extrusion deformation, and the grain refinement effect of the magnesium alloy bar is more remarkable.
Drawings
FIG. 1 is a schematic diagram of a front view of a mold according to the present invention;
FIG. 2 is a top view of the channel outer frame of the mold of the present invention;
figure 3 is a front and top view of the upper thread punch of figure 1;
FIG. 4 is a detail view of the left hand twist extrusion die crank link portion of FIG. 1;
FIG. 5 is a detail view of the right side torsional extrusion die drive section of FIG. 1;
FIG. 6 is a detail view of the left and right side torsion extrusion bars;
FIG. 7 is a schematic view of a torsionally extruded channel;
FIG. 8 is a schematic illustration of the shape of a billet within a torsionally extruded channel.
In the figure: 1-a movable cross beam; 2-a threaded male die fixing plate; 3-stand columns; 4-a first bearing; 5-a threaded male die; 6-a first threaded pipe; 7-a first support bar; 8-a wheel disc; 9-connecting rod; 10-a first motor; 11-a universal ball; 12-a second support bar; 13-a second threaded pipe; 14-left side torsion extrusion rod; 15-front module; 16-right side torsion extrusion rod; 17-a threaded rod; 18-a power sleeve; 19-a second bearing; 20-positioning a sleeve; 21-a third support bar; 22-a second motor; 23-a fourth support bar; 24-a central console; 25-an oil temperature machine controller; 26-a movable beam controller; 27-a vacuum atmosphere heating furnace controller; 28-conducting wires; 29-stop button; 30-a start button; 31-emergency stop button; 32-a display screen; 33-heating channels; 34-cross-shaped protrusions; 35-left groove; 36-right groove; 37-a working platform; 38-backing plate; 39-bolts; 40-magnesium alloy bar stock; 41-post module.
I-torsion pushing area; II, a dynamic torsion extrusion area; III-extrusion zone.
Detailed Description
The invention is described in further detail below with reference to the drawings and examples.
The utility model provides a diversified device of little texture magnesium alloy of fine grain of dynamic torsion extrusion preparation high performance, includes vertical extruder, upper portion twists reverse extrusion mould, left side twists reverse extrusion mould, right side twists reverse extrusion mould, outside die carrier and power device, wherein:
the vertical extruder comprises a movable cross beam 1, a stand column 3 and a working platform 37. The two upright posts 3 are vertically upwards arranged above the working platform 37, and the movable cross beam 1 spans above the upright posts 3 and can move up and down along the upright posts 3;
the upper torsion extrusion die comprises a threaded male die fixing plate 2, a first bearing 4, a threaded male die 5 and a first threaded pipe 6; the screw thread male die fixing plate 2 is arranged below the movable cross beam 1, the first bearing 4 is arranged below the screw thread male die fixing plate 2 and is assembled with the screw thread male die 5, the screw thread male die 5 is sleeved with a first screw thread pipe 6 meshed with the screw thread male die 5, the first screw thread pipe 6 is fixed on the upright post 3 on the right side of the extruder through a fourth supporting rod 23, and the front end of the screw thread male die 5 is provided with a crossA shaped protrusion 34 having a front angle θ 3 The blank is used for fixing the blank;
the left side torsion extrusion die comprises a left side torsion extrusion rod 14, a second threaded pipe 13, a universal ball 11, a connecting rod 9 and a wheel disc 8. The wheel disc 8 is rotatably supported on the left upright post 3 through a first supporting rod 7, the left end of the connecting rod 9 is hinged to the edge of the wheel disc 8 and rotates together with the wheel disc 8, the right end of the connecting rod 9 is connected with the universal ball 11, the other end of the universal ball 11 is connected with the left torsion extrusion rod 14, the second threaded pipe 13 is fixed on the left upright post 3 through a second supporting rod 12, the upper half part of the left torsion extrusion rod 14 is a threaded rod matched with the second threaded pipe 13, the cross section of the lower half part is gradually reduced, an asymmetric left groove 35 is formed, the wheel disc 8 is driven to rotate through the first motor 10, the connecting rod 9 is driven to rotate, and the connecting rod 9 drives the torsion extrusion rod 14 to twist and advance under the condition of being matched with the threaded pipe 13;
The right side torsion extrusion die comprises a right side torsion extrusion rod 16, a second bearing 19, a positioning sleeve 20, a power sleeve 18 and a threaded rod 17. The whole die is fixed on a column 3 at the right side of the extruder through a third supporting rod 21 (a positioning sleeve 20 is connected with the third supporting rod 21), wherein a threaded rod 17 penetrates through the positioning sleeve 20, a power sleeve 18 and a right side torsion extrusion rod 16, the positioning sleeve 20 is fixed on the threaded rod 17 through a bearing, the threaded rod 17 can freely rotate, the power sleeve 18 is embedded in the positioning sleeve 20, the power sleeve 20 is fixed in the circumferential direction through edge slotting and moves up and down by the length of the positioning sleeve 20, the threaded rod 17 and the power sleeve 18 are in threaded connection, a second bearing 19 is installed in the power sleeve 18, the second bearing 19 is matched with the right side torsion extrusion rod 16 (the right side torsion extrusion rod 16 is connected with a second bearing inner ring), the upper half part of the right side torsion extrusion rod 16 is hollow, the inner surface is provided with a protruding part axially parallel to the right side torsion extrusion rod 16, the 17 surface is provided with a groove (through threads), the protruding part of the right side torsion extrusion rod 16 is embedded with the groove of the threaded rod 17 (the right side torsion extrusion rod 16 can be driven by the power sleeve 18 to advance or retreat and synchronously rotate), the right side torsion extrusion rod 16 is gradually provided with a left side extrusion groove 36, and the left side extrusion cross section area of the right side extrusion rod is gradually reduced by the left side extrusion groove 35 is provided with a left side extrusion groove 35;
The outer mould frame is arranged on a backing plate 38 fixed above the working platform 37, comprising a front module 15 and a rear module 41. The front module 15 and the rear module 41 are fixed through four bolts 39, an extrusion space is formed in the rear module 41, and the extrusion space comprises a vertical middle channel and left and right channels which are formed on the left side and the right side of the rear module 41 and communicated with the bottom of the middle channel and are obliquely arranged; the working platform 37 and the backing plate 38 are provided with a material leakage hole which is communicated with the middle channel and has an inner diameter smaller than that of the middle channel; the threaded male die 5 extends into the middle channel from top to bottom, and the left and right torsion extrusion rods extend into the left and right channels respectively; the middle channel, the left channel and the right channel together with the material leakage holes form a torsion extrusion channel; and heating channels 33 through which the organic heat carrier flows are provided inside each of the front module 15 and the rear module 41;
the power mechanism is a first motor 10 and a second motor 22 for driving the left and right torsion extrusion dies; the motors are two-way motors.
Further, the torsion extrusion channel is sequentially provided with a torsion pushing area I, a dynamic torsion extrusion area II and an extrusion area III from top to bottom. In the torsion pushing area I, the magnesium alloy bar 40 is continuously twisted and advanced under the drive of the thread male die 5, and the advancing speed of the thread male die 5 is V 3 Torsion angular velocity is omega 3 The method comprises the steps of carrying out a first treatment on the surface of the Reaching the dynamic torsion extrusion area II, respectively carrying out dynamic torsion extrusion at different advancing speeds and different torsion angle speeds through the dynamic torsion extrusion rods at the left side and the right side, and driving the wheel disc to rotate by the first motor at the left side, wherein the rotation angle speed omega of the wheel disc is higher than the rotation angle speed omega of the wheel disc 4 The left torsion extrusion rod is driven to advance and rotate, and the advancing speed of the left torsion extrusion rod is V 1 Torsion angular velocity is omega 1 The threaded rod in the right-side torsion extrusion die is driven by the second motor to rotate, and the rotation angular speed of the threaded rod is omega 5 The advancing speed of the right torsion extrusion rod is driven to be V 2 Torsion angular velocity is omega 2 And V is 1 ≠V 2 ≠V 3 ，ω 1 ≠ω 2 ≠ω 3 Further increases asymmetric deformation, forces the c-axis of the magnesium alloy blank to deflect, and refines grains. Meanwhile, the front end parts of the left torsion extrusion rod and the right torsion extrusion rod are respectively provided with an asymmetric left groove 35 and a right groove 36, and the inner radius of the left groove at the front end of the left torsion extrusion rod is r 1 The inner radius of the right groove at the front end of the right torsion extrusion rod is r 2 Two asymmetric r 1 ≠r 2 The angles between the two torsion extrusion rods and the rear module are respectively theta 1 And theta 2 Simultaneously, the torsion extrusion rods on the left side and the right side and the torsion direction of the upper threaded male die are opposite in the left side of the contact part, and the right side is the same in direction, so that the friction force on the two sides is different, the plastic deformation of the magnesium alloy blank is further enhanced, the texture refinement grains are weakened, and finally, the magnesium alloy blank reaches the required high-performance magnesium alloy bar through the extrusion area III. The device can realize the preparation of the fine-grain weak texture magnesium alloy through multidirectional dynamic torsion extrusion deformation.
Further, the front module 15, the rear module 41, the left side torsion extrusion rod 14, the right side torsion extrusion rod 16 and the thread male die 5 are all made of 4Cr5MoSiV1 hot work die steel.
Further, the surface roughness of the left torsion extrusion rod 14 is Ra0.08-0.16 μm, the surface roughness of the right torsion extrusion rod 16 is Ra0.16-0.4 μm, and the surface roughness of the rear module torsion extrusion channel is Ra0.4-0.8 μm. The torsional extrusion channel and the roughness of the left torsional extrusion rod and the right torsional extrusion rod form asymmetric distribution, so that the difference value is formed between the extrusion process and the friction force generated by the blank, the differential flow of the blank is further promoted, and shearing extrusion deformation is generated to weaken the basal plane texture of the blank.
In the specific embodiment, materials and chemical reagents required in the preparation process are selected before the magnesium alloy with fine grain and weak texture is prepared by reciprocating torsional extrusion deformation:
1. magnesium alloy bar stock: the cylindrical blank is made of AZ31, 96% of magnesium, 3% of aluminum and 1% of zinc;
2. sand paper: a solid state solid;
3. graphite oil solution: a viscous liquid;
4. absolute ethyl alcohol: liquid with purity of 99.5%;
5. acetone: liquid with 99% purity.
A method for preparing a high-performance fine grain weak texture magnesium alloy bar by multidirectional dynamic torsion extrusion comprises the following steps:
S1, preprocessing magnesium alloy bar blanks:
s1-1, processing a magnesium alloy bar blank into a cylindrical magnesium alloy bar 40, polishing the surface of the magnesium alloy bar 40 by using 600-mesh sand paper to remove greasy dirt, and sequentially polishing by using 800-mesh, 1000-mesh and 1200-mesh sand paper until the surface of the magnesium alloy bar 40 is smooth;
s1-2, mixing acetone and absolute ethyl alcohol in a cleaning tank according to a volume ratio of 3:2, and uniformly stirring to prepare cleaning liquid;
s1-3, immersing the magnesium alloy bar 40 prepared in the step S1-1 into the cleaning solution prepared in the step S1-2, placing the cleaning tank on an ultrasonic cleaner to ultrasonically clean the magnesium alloy bar 40 for 60min, then taking out the magnesium alloy bar 40, cleaning with absolute ethyl alcohol, and finally drying with a blower;
s1-4, coating graphite oil solution on the surface of the magnesium alloy bar 40 prepared in the step S1-3 for later use;
s2, preheating the magnesium alloy bar 40: setting the heating temperature of a vacuum atmosphere heating furnace to be 450 ℃, and after the heating furnace temperature reaches the set temperature, placing the magnesium alloy bar 40 into the heating furnace, and preserving the heat for 3 hours;
s3, lubrication, assembly and preheating of the dynamic torsional extrusion deformation forming device:
s3-1, lubrication: coating graphite oil solution on the surfaces of the thread male die 5, the left side torsion extrusion rod 14, the right side torsion extrusion rod 16, the power sleeve 18, the contact part between the positioning sleeve 20 and the second bearing 19 and the right side torsion extrusion rod 16, and the inner surfaces of the torsion extrusion channels I, II and III;
S3-2, assembling:
firstly, a backing plate 38 is installed and fixed on a working platform 37 of a vertical extruder, a rear module 41 and a front module 15 are installed together through four bolts 39 and fixed on the backing plate 38, then a left torsion extrusion rod 14 is assembled and led into a left channel of the rear module 41 and matched with a second threaded pipe 13, the upper part of the left torsion extrusion rod 14 is connected with a connecting rod 9 and a wheel disc 8 through a universal ball 11, then a threaded rod 17 in a right torsion extrusion die penetrates into a positioning sleeve 20, a power sleeve 18 and a right torsion extrusion rod 16, the power sleeve 18 and the right torsion extrusion rod 16 are installed together, the positioning sleeve 20 is circumferentially fixed with the power sleeve 18, the power sleeve 18 moves up and down along the edge of the positioning sleeve 20, the power sleeve 18, a second bearing 19 and the right torsion extrusion rod 16 are assembled and led into a right channel, and the position of a discharge hole is aligned with a leakage hole which penetrates through the working platform and the backing plate;
s3-3, preheating: controlling the medium temperature of the heating channel 33 to be 300-500 ℃, and preserving heat for 2-4 hours after the medium temperature reaches the set temperature for later use;
s4, multidirectional dynamic torsion extrusion forming: the middle channel, the left channel and the right channel together with the material leakage holes form a torsion extrusion channel; the torsion extrusion space comprises a torsion pushing area I, a dynamic torsion extrusion area II and an extrusion area III which are arranged from top to bottom;
S4-1, withdrawing the thread male die 5 from the channel, filling the magnesium alloy bar 40 in the torsion pushing area I, and then pushing the thread male die 5 into the channel; operating the vertical extruder, pushing the threaded male die 5 downwards, driving the magnesium alloy bar 40 to rotate and push downwards; when the magnesium alloy bar 40 reaches the dynamic torsion extrusion area II, the first motor 10 on the left side drives the wheel disc 8 to rotate, the wheel disc 8 drives the connecting rod 9 to rotate, the left torsion extrusion rod 14 is pushed to twist and extrude the blank forwards, the second motor 22 on the right side drives the threaded rod to rotate, the power sleeve 18 is driven to advance forwards, and meanwhile the right torsion extrusion rod 16 is driven to rotate and advance forwards, and the magnesium alloy bar 40 is extruded; in the process, the magnesium alloy bar 40 is driven to twist along with the threaded male die 5 at the top, so that the magnesium alloy bar 40 is spirally advanced in the left-right asymmetric spiral extrusion process, the c-axis of the magnesium alloy bar is deflected, and the weakened texture and crystal grains are further refined; when magnesium alloy bar 40 reaches extrusion zone iii, the billet is further extruded to achieve the desired uniform texture of the magnesium alloy bar. In the process of torsion extrusion forming, controlling the temperature of the heating wire to be 300-500 ℃;
S4-2, taking out the magnesium alloy bar prepared in the step S4-1, polishing the surface of the magnesium alloy bar by using sand paper, cleaning the magnesium alloy bar by using the cleaning liquid prepared in the step S1-2, and finally, secondarily cleaning by using absolute ethyl alcohol, and drying by using a blower to prepare the fine-grain weak-texture high-performance magnesium alloy bar capable of being directly put into use.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
A device and a process method for preparing a fine-grain weak texture magnesium alloy bar by multidirectional dynamic torsion extrusion adopt the following steps:
(1) The upper torsion extrusion die and the external die carrier are arranged on the vertical extruder, the torsion extrusion dies on the left side and the right side are arranged in the channels on the left side and the right side, the installation is firm, the connection relation of the positions of all parts is correct, and the sequential operation is performed;
(2) Polishing the outer surface of the AZ31 magnesium alloy bar blank by using 600-mesh sand paper to remove greasy dirt, and then sequentially polishing by using 1000, 1200 and 2500-mesh sand paper to ensure that the surface is clean and smooth; placing the polished magnesium alloy bar blank into a mixed solution of acetone and absolute ethyl alcohol in a volume ratio of 3:2 for ultrasonic cleaning for 30min, and then cleaning with alcohol and drying with a blower;
(3) Starting a vacuum atmosphere heating furnace to preheat the magnesium alloy bar blank, wherein the preset temperature is 400 ℃, and continuously placing the magnesium alloy bar blank into the heating furnace to keep the temperature for 3 hours when the preset temperature is reached;
(4) Starting a torsion extrusion die cavity heating device, heating the I and II areas of the torsion extrusion channel, presetting the heating temperature to 400 ℃, and continuing to keep the temperature for 3 hours after the heating temperature reaches the preset temperature;
(5) The surface of the magnesium alloy bar blank is coated with high-temperature graphite oil solution for lubrication, the external dimensions of the left torsion extrusion rod 14 and the right torsion extrusion rod 16 are the same, but the dimensions of the left groove 35 and the right groove 36 in the left torsion extrusion rod are different, the preheated magnesium alloy bar blank is placed in the torsion extrusion die cavity I, the threaded male die 5 stretches into the torsion pushing area I, and the cross-shaped protrusions 34 on the surface of the threaded male die are inserted into the magnesium alloy bar blank to be fixed into a whole.
(6) In the invention, the front module 15, the rear module 41, the left torsion extrusion rod 14, the right torsion extrusion rod 16 and the thread male die 5 are all made of 4Cr5MoSiV1 hot work die steel. The surface roughness of the left torsion extrusion rod 14 is Ra0.08-0.16 mu m, the surface roughness of the right torsion extrusion rod 16 is Ra0.16-0.4 mu m, and the surface roughness of the rear module torsion extrusion channels I, II and III is Ra0.4-0.8 mu m.
(7) And starting a motor of the vertical extruder, setting the pressure to 400MPa, and starting motors at the left side and the right side. The vertical extruder pushes the threaded male die to downwards advance and rotate, and the angular speed of the threaded male die is omega 3 =0.05r/s, travel speed V 3 The wheel disc is driven to rotate under the action of a left motor with the rotation angular speed omega of the motor of 50mm/min 4 The wheel disc drives the connecting rod to drive the left torsion extrusion rod to twist forward, and the advancing speed of the left torsion extrusion rod is V 1 The torsion angle speed is ω =60 mm/min 1 The threaded rod in the right-side torsion extrusion die is driven by the second motor to rotate, and the rotation angular speed of the threaded rod is omega 5 =0.15 r/s, the travel speed of the right torsion extrusion rod is driven to be V 2 The torsion angle speed is ω=70 mm/min 2 =0.15r/s, further increasing the asymmetric deformation, forcing the c-axis deflection of the magnesium alloy billet, refining the grains. Meanwhile, the front end parts of the left torsion extrusion rod and the right torsion extrusion rod are respectively provided with an asymmetric left groove 35 and a right groove 36, and the inner radius of the left groove at the front end of the left torsion extrusion rod is r 1 The inner radius of the right groove at the front end of the right torsion extrusion rod is r 2 =5mm, the angles between the two torsion extrusion bars and the rear module are respectively θ 1 And theta 2 The experiment is set as theta 1 =45° and θ 2 The plastic deformation of the magnesium alloy blank is further aggravated, the texture refinement grains are weakened, and finally, the spiral blank is further extruded through the extrusion area III to reach the required size of the magnesium alloy bar, so that the processing process of the magnesium alloy bar is realized.
(8) Taking out the magnesium alloy bar, polishing the surface of the magnesium alloy bar by using sand paper, then placing the magnesium alloy bar in a mixed solution of acetone and absolute ethyl alcohol in a volume ratio of 3:2 for ultrasonic cleaning, and finally cleaning by using alcohol and drying by using a blower to blow.
Conclusion: according to the device and the process method for preparing the fine-grain weak texture magnesium alloy bar through multidirectional dynamic torsion extrusion, the average grain size of the magnesium alloy blank is greatly reduced compared with that of a conventional magnesium alloy, the average grain size is reduced to 2.55 mu m from original 35 mu m, the basal plane texture is effectively weakened compared with that of an initial magnesium alloy bar, and the mechanical property of the magnesium alloy is effectively improved.
The materials and chemical reagents used are as follows: AZ31 magnesium alloy block-shaped billet with diameter d=50mm; sand paper: siC,600 meshes, 2 sheets; 1000 meshes, 2 sheets; 1200 meshes, 2 sheets; 2500 meshes, 2 sheets; high temperature graphite oil solution: c,500g; absolute ethyl alcohol: CH3CH2OH, 1200ml; acetone: C3H6O,800ml.
The principle of the invention for obtaining the fine-grain weak texture magnesium alloy through the steps is described in detail below with reference to the accompanying drawings:
1) Dimensional parameters of torsion extrusion bars: the torsion extrusion rods on the left side and the right side are firstly that the angles between the rods and the external die carrier are different
Figure 107220DEST_PATH_IMAGE001
Secondly, the angular and travelling speeds of the two are also different from those of the threaded male die, i.e. V 1 ≠V 2 ≠V 3 ，ω 1 ≠ω 2 ≠ω 3 . The minimum inner diameters of the grooves on the left side and the right side are also different, r 1 ≠r 2 。
2) Dynamic torsion extrusion process: when the magnesium alloy blank is extruded downwards by the thread male die and reaches a dynamic torsion extrusion area II, the magnesium alloy blank is respectively subjected to dynamic screw extrusion of left and right torsion extrusion rods, the left and right torsion extrusion rods are respectively subjected to torsion extrusion, the descending speed and the torsion speed are respectively different, in addition, the groove parts are asymmetric, and meanwhile, the torsion extrusion rods on the left and right sides are respectively different from the torsion direction of the upper thread male die at the contact part, so that the friction force on the two sides is different, the deformation of magnesium alloy is further aggravated, and the purpose of grain refinement is achieved. The magnesium alloy blank is subjected to asymmetric dynamic spiral extrusion, the blank is changed into an asymmetric spiral shape from a rod shape, the c axis of the blank crystal grain is deflected to weaken the basal plane texture and refine crystal grains, and finally the deformed blank is extruded into a bar through an extrusion area III to further weaken the basal plane texture refinement crystal grains.
3) Surface roughness difference: the torsion extrusion rods on the left side and the right side are opposite to the torsion direction of the upper threaded male die at the contact position, and the right side is the same direction, so that the friction forces on the two sides are different. Meanwhile, in the parts forming the extrusion channels, the surface roughness of the left torsion extrusion rod 14 is Ra0.08-0.16 mu m, the surface roughness of the right torsion extrusion rod 16 is Ra0.16-0.4 mu m, and the surface roughness of the rear module torsion extrusion channels I, II and III is Ra0.4-0.8 mu m. The difference of the surface roughness can directly lead to the difference of friction coefficients of the corresponding surfaces and the surfaces of the magnesium alloy billets, so that the magnesium alloy billets close to the surfaces have uneven flow speed in the deformation process, the c-axis of the grains of the magnesium alloy billets is further deflected on the basis of the size parameters of the torsion extrusion rod and the dynamic torsion extrusion process, and the basal plane texture of the magnesium alloy billets is further weakened and the grains are thinned.
Through the three-point principle, the magnesium alloy blank is finally subjected to a large amount of shearing extrusion deformation, and the high-performance magnesium alloy bar with the weak basal plane texture is obtained.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present invention should be included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (7)

1. The device for preparing the high-performance fine grain weak texture magnesium alloy by multi-azimuth dynamic torsion extrusion is characterized by comprising a vertical extruder, an upper torsion extrusion die, a left torsion extrusion die, a right torsion extrusion die, an external die carrier and a power device, wherein:
the vertical extruder comprises a movable cross beam (1), two upright posts (3) and a working platform (37); the two upright posts (3) are vertically upwards arranged above the working platform (37), and the movable cross beam (1) spans over the upright posts (3) and can move up and down along the upright posts (3);
the upper torsion extrusion die comprises a threaded male die fixing plate (2), a first bearing (4), a threaded male die (5) and a first threaded pipe (6), wherein the threaded male die fixing plate (2) is arranged below the movable cross beam (1), the first bearing (4) is axially and vertically arranged below the threaded male die fixing plate (2) and is assembled with the threaded male die (5), the threaded male die (5) is sleeved with the first threaded pipe (6) meshed with the threaded male die, and the first threaded pipe (6) is fixed on a stand column (3) on the right side of the extruder through a fourth supporting rod (23);
The left side torsion extrusion die comprises a left side torsion extrusion rod (14), a second threaded pipe (13), a universal ball (11), a connecting rod (9) and a wheel disc (8); the wheel disc (8) is rotatably supported on the left upright post (3) through a first supporting rod (7), the left end of the connecting rod (9) is hinged to the edge of the wheel disc (8), the connecting rod rotates together with the wheel disc (8), the right end of the connecting rod (9) is connected with a universal ball (11), the universal ball (11) is arranged at the top of a left torsion extrusion rod (14), a second threaded pipe (13) is fixed on the left upright post (3) through a second supporting rod (12), the upper half part of the left torsion extrusion rod (14) is a threaded rod matched with the second threaded pipe (13), the cross section of the lower half part of the left torsion extrusion rod is gradually reduced, and an asymmetric left groove (35) is formed;
the right-side torsion extrusion die comprises a right-side torsion extrusion rod (16), a second bearing (19), a positioning sleeve (20), a power sleeve (18) and a threaded rod (17); the right side torsion extrusion die is fixed on a stand column (3) on the right side of the extruder through a third support rod (21), wherein a threaded rod (17) penetrates through the inside of a positioning sleeve (20), a power sleeve (18) and a torsion extrusion rod (16), the positioning sleeve (20) is fixed on the threaded rod (17) through a bearing, the threaded rod (17) can freely rotate, the power sleeve (18) is embedded in the inside of the positioning sleeve (20), is circumferentially fixed with the positioning sleeve (20) through edge slotting and is limited by the length of the positioning sleeve (20) to move up and down, the threaded rod (17) is in threaded connection with the power sleeve (18), the power sleeve (18) is internally provided with a second bearing (19), the second bearing (19) is matched with the right torsion extrusion rod (16), the upper half part of the right torsion extrusion rod (16) is hollow, the inner surface of the right torsion extrusion rod is provided with a protruding part axially parallel to the right torsion extrusion rod, the surface of the threaded rod (17) is provided with a groove axially parallel to the threaded rod, the protruding part of the right torsion extrusion rod (16) is embedded with the groove of the threaded rod (17), the lower half part of the right torsion extrusion rod (16) is a solid rod with a gradually reduced cross section and provided with a right groove (36), and the right groove (36) and the left groove (35) of the left torsion extrusion rod are partially asymmetric;
The external die carrier is arranged on a base plate (38) fixed above the working platform (37) and comprises a front module (15) and a rear module (41); the front module (15) and the rear module (41) are fixed through bolts (39), an extrusion space is formed in the rear module (41), and the extrusion space comprises a vertical middle channel and left and right channels which are formed on the left side and the right side of the rear module (41) and communicated with the bottom of the middle channel and are obliquely arranged; the working platform (37) and the backing plate (38) are provided with a material leakage hole which is communicated with the middle channel and has an inner diameter smaller than that of the middle channel; the threaded male die (5) stretches into the middle channel from top to bottom, and the left and right torsion extrusion rods respectively stretch into the left and right channels; the middle channel, the left channel and the right channel together with the material leakage holes form a torsion extrusion channel; heating channels (33) for the flow of the organic heat carrier are arranged in the front module (15) and the rear module (41);
the power mechanism is a first motor (10) and a second motor (22) for driving the left and right torsion extrusion dies; wherein the first motor (10) drives the wheel disc (8) to rotate, and the second motor (22) drives the threaded rod (17) to rotate.
2. The apparatus for preparing high-performance fine grain and weak texture magnesium alloy by multi-directional dynamic torsion extrusion as claimed in claim 1, wherein the rotation directions of the left torsion extrusion rod and the right torsion extrusion rod are opposite.
3. The device for preparing the high-performance fine grain weak texture magnesium alloy by multidirectional dynamic torsion extrusion according to claim 1, wherein the front end of the thread male die (5) is provided with a cross-shaped protrusion (34).
4. The device for preparing the high-performance fine grain and weak texture magnesium alloy by multi-azimuth dynamic torsion extrusion according to claim 1, wherein the front module (15), the rear module (41), the left torsion extrusion rod (14), the right torsion extrusion rod (16) and the thread male die (5) are all made of 4Cr5MoSiV1 hot working die steel.
5. The device for preparing the high-performance fine grain and weak texture magnesium alloy by multi-azimuth dynamic torsion extrusion according to claim 1, wherein the surface roughness of the left torsion extrusion rod (14) is Ra0.08-0.16 mu m, the surface roughness of the right torsion extrusion rod (16) is Ra0.16-0.4 mu m, and the surface roughness of the rear module extrusion space is Ra0.4-0.8 mu m.
6. A process method for preparing a high-performance fine grain weak texture magnesium alloy bar by multidirectional dynamic torsion extrusion is characterized by comprising the following steps:
s1, preprocessing magnesium alloy bar blanks:
s1-1, processing a magnesium alloy bar blank into a cylindrical magnesium alloy bar (40), polishing the surface of the magnesium alloy bar by using 600-mesh sand paper to remove greasy dirt, and sequentially polishing by using 800-mesh, 1000-mesh and 1200-mesh sand paper until the surface of the magnesium alloy bar (40) is smooth;
S1-2, mixing acetone and absolute ethyl alcohol in a cleaning tank according to a volume ratio of 3:2, and uniformly stirring to prepare cleaning liquid;
s1-3, immersing the magnesium alloy bar (40) prepared in the step S1-1 into the cleaning solution prepared in the step S1-2, placing the cleaning tank on an ultrasonic cleaner to ultrasonically clean the magnesium alloy bar (40) for 60min, then taking out the magnesium alloy bar (40), cleaning with absolute ethyl alcohol, and finally drying with a blower;
s1-4, coating graphite oil solution on the surface of the magnesium alloy bar (40) prepared in the step S1-3 for later use;
s2, preheating a magnesium alloy bar (40): setting the heating temperature of a vacuum atmosphere heating furnace to be 450 ℃, and after the heating furnace temperature reaches the set temperature, placing the magnesium alloy bar (40) into the heating furnace, and preserving the heat for 3 hours;
s3, lubrication, assembly and preheating of the dynamic torsional extrusion deformation forming device:
s3-1, lubrication: smearing graphite oil solution on the surfaces of the thread male die (5), the left torsion extrusion rod (14), the right torsion extrusion rod (16), the power sleeve (18), the contact part between the positioning sleeve (20) and the second bearing (19) and the right torsion extrusion rod (16) and the inner surface of the torsion extrusion channel;
S3-2, assembling:
firstly, a backing plate (38) is installed and fixed on a working platform (37) of a vertical extruder, a rear module (41) and a front module (15) are installed together through four bolts (39) and fixed on the backing plate (38), then a left torsion extrusion rod (14) is assembled and led into a left channel of the rear module (41) and matched with a second threaded pipe (13), the upper part of the left torsion extrusion rod (14) is connected with a connecting rod (9) and a wheel disc (8) through a universal ball (11), a threaded rod (17) in a right torsion extrusion die is penetrated into a positioning sleeve (20), a power sleeve (18) and a right torsion extrusion rod (16), the power sleeve (18) and the right torsion extrusion rod (16) are installed, the positioning sleeve (20) and the power sleeve (18) are circumferentially fixed, the power sleeve (18) moves up and down along the edge of the positioning sleeve (20), the power sleeve (18) and the second bearing (19) and the right torsion extrusion rod (16) are matched, and then the right torsion extrusion rod (16) is assembled and extruded into a discharge hole (37) through the right channel and the position of the backing plate;
s3-3, preheating: controlling the temperature of the medium in the heating channel (33) to be 300-500 ℃, and preserving heat for 2-4 hours after the temperature reaches the set temperature for later use;
S4, multidirectional dynamic torsion extrusion forming: the middle channel, the left channel and the right channel together with the material leakage holes form a torsion extrusion channel; the torsion extrusion channel comprises a torsion pushing area I, a dynamic torsion extrusion area II and an extrusion area III which are arranged from top to bottom;
s4-1, withdrawing the thread male die (5) from the torsion extrusion channel, filling the magnesium alloy bar (40) in the torsion pushing area I, and pushing the thread male die (5) into the torsion extrusion channel; operating the vertical extruder, and pushing the threaded male die (5) downwards to drive the magnesium alloy bar (40) to rotate and push downwards; when the magnesium alloy bar (40) reaches a dynamic torsion extrusion area II, a first motor (10) at the left side drives a wheel disc (8) to rotate, the wheel disc (8) drives a connecting rod (9) to rotate so as to push a left torsion extrusion rod (14) to twist and extrude a blank forwards, a second motor (22) at the right side drives a threaded rod (17) to rotate, a power sleeve (18) is driven to advance forwards, and meanwhile, a right torsion extrusion rod (16) is driven to rotate and advance forwards, and the magnesium alloy bar (40) is extruded; in the process, the magnesium alloy bar (40) is driven to twist along with the threaded male die (5) at the top, so that the magnesium alloy bar (40) realizes spiral advance in the left-right asymmetric spiral extrusion process, the c-axis of the magnesium alloy blank deflects, and the weakened texture and the grains are further refined; when the magnesium alloy bar (40) reaches the extrusion area III, the blank is further extruded to reach the magnesium alloy bar with uniform required structure; in the process of torsion extrusion forming, controlling the temperature of a medium in a heating channel (33) to be 300-500 ℃;
S4-2, taking out the magnesium alloy bar prepared in the step S4-1, polishing the surface of the magnesium alloy bar by using sand paper, cleaning the magnesium alloy bar by using the cleaning liquid prepared in the step S1-2, and finally, secondarily cleaning by using absolute ethyl alcohol, and drying by using a blower to prepare the fine-grain weak-texture high-performance magnesium alloy bar capable of being directly put into use.
7. As claimed in claim 6A process for preparing high-performance fine-grain weak-texture magnesium alloy bar by multidirectional dynamic torsion extrusion is characterized in that a magnesium alloy bar (40) is continuously twisted and advanced under the drive of a thread male die (5) in a torsion pushing area, and the advancing speed of the thread male die is V 3 Torsion angular velocity is omega 3 The method comprises the steps of carrying out a first treatment on the surface of the Reaching the dynamic torsion extrusion area II, respectively carrying out dynamic torsion extrusion at different advancing speeds and different torsion angle speeds through torsion extrusion rods at the left side and the right side, and driving the wheel disc to rotate by a first motor (10) at the left side, wherein the rotation angle speed omega of the wheel disc is higher than that of the wheel disc 4 The left torsion extrusion rod (14) is driven to advance and rotate, and the advancing speed of the left torsion extrusion rod (14) is V 1 Torsion angular velocity is omega 1 The threaded rod (17) in the right-side torsion extrusion die is driven by the second motor (22) to rotate, and the rotation angular speed of the threaded rod (17) is omega 5 The advancing speed of the right torsion extrusion rod (16) is driven to be V 2 Torsion angular velocity is omega 2 And V is 1 ≠V 2 ≠V 3 ，ω 1 ≠ω 2 ≠ω 3 。
CN202211570745.2A 2022-12-08 2022-12-08 Device and process method for preparing high-performance fine-grain weak-texture magnesium alloy by multidirectional dynamic torsion extrusion Pending CN116159878A (en)

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