CN110814076B - Mould and forming method for preparing high-performance ultra-fine grain light alloy pipe - Google Patents

Abstract

The invention discloses a die and a forming method for preparing a high-performance ultrafine-grained light alloy pipe, wherein the die comprises an extrusion rod, a female die and an elastic ejector mechanism, the female die consists of an inner female die and an outer female die, a vertical through hole for accommodating a blank to be processed is arranged in the middle of the inner female die, a pipe forming cavity is formed between the inner female die and the outer female die, and the pipe forming cavity consists of an upper sizing area and a lower reducing shearing area; after the press machine is started, the press machine can drive the extrusion rod to move downwards in the vertical through hole, reverse extrusion of the blank is achieved, and the concave die can be driven to slide up and down and be positioned at a forming position. The mould and the forming method for preparing the high-performance ultra-fine grain light alloy pipe have the advantages of simple mould structure, high pipe forming automation degree and good forming quality.

Description

Mould and forming method for preparing high-performance ultra-fine grain light alloy pipe

Technical Field

The invention belongs to the field of alloy pipe processing, and particularly relates to a die and a forming method for preparing a high-performance ultra-fine grain light alloy pipe.

Background

At present, ultra-fine grain alloy (light alloy) pipes, especially thin-wall and high-precision light alloy pipes, are mainly formed by extrusion. The extrusion processing not only can improve the plasticity of the alloy, but also can effectively refine crystal grains to obtain the light alloy pipe with high performance. However, the conventional extrusion method has the following disadvantages: in the extrusion production process, forward extrusion is generally adopted, but the friction between the blank and an extrusion container is large during the forward extrusion, the metal flow is not uniform, and the forward extrusion can form a banded structure and a strong basal texture along the extrusion direction of the pipe, so that the anisotropy of the pipe is caused, and the mechanical property of the formed pipe is reduced. The formed basal texture is easy to cause the defects of shrinkage cavity, looseness and the like in the light alloy casting structure in the secondary processing of the thin pipe, so that the processing precision of the pipe, particularly the thin pipe is poor.

Based on the above-mentioned drawbacks of forward extrusion, the applicant considered to machine light alloy pipes using the direction of backward extrusion. Aiming at a forming process for preparing an alloy pipe by reverse extrusion, the magnesium alloy thin-wall pipe with modified surface, which is announced by the intellectual property agency of China in 2019, 10, 11 and has the announcement number of 106362220, as well as a reverse extrusion die and a preparation method thereof. When the extrusion die is used for extrusion, the mandrel needs to be lifted, then the heated alloy cast ingot is placed into an extrusion cylinder, and then an extrusion female die is placed into the extrusion cylinder and placed on the alloy cast ingot; and starting the press machine to enable the lower die part to move upwards, reversely extruding the blank by the extrusion rod, enabling the alloy pipe to penetrate out upwards from the hollow interior of the extrusion rod, ending the reverse extrusion deformation process, resetting the piston of the extruder, enabling the lower die part to fall down, drawing off the plug, discharging, and ending the reverse extrusion to obtain the Mg-Zn-Sr alloy pipe. The mold structure of this application is comparatively complicated, simultaneously, after the extrusion is accomplished, can not be automatic ejecting with shaping tubular product. In addition, the pipe prepared by the traditional backward extrusion method is easy to crack and has low forming rate.

Disclosure of Invention

Aiming at the defects of the prior art, the technical problems to be solved by the invention are as follows: how to provide a mould and a forming method for preparing a high-performance ultra-fine grain light alloy pipe with simple structure, high pipe forming automation degree and good forming quality.

In order to solve the technical problems, the invention adopts the following technical scheme:

a mould for preparing high-performance and ultra-fine grain light alloy pipes comprises an extrusion rod, a female die and an elastic jacking member mechanism, and is characterized in that the female die consists of an inner female die and an outer female die, wherein a vertical through hole for accommodating a blank to be processed is arranged in the middle of the inner female die, a cavity with the shape and the size consistent with the shape and the outer diameter of the light alloy pipe to be prepared is arranged in the middle of the outer female die, the upper end of the inner female die is fixedly arranged on an outer cross beam of a press machine, the lower end of the inner female die is arranged in the cavity of the outer female die and coaxial with the outer female die, the outer end surface of the inner female die is consistent with the shape and the inner diameter of the light alloy pipe to be prepared, a pipe forming cavity is formed between the outer end surface of the inner female die and the cavity of the outer female die, the pipe forming cavity consists of an upper sizing area and a lower reducing shearing area, and is communicated with the vertical through hole; one end of the extrusion rod is fixedly arranged on an inner cross beam of the press machine, the other end of the extrusion rod is arranged in the vertical through hole of the inner concave die, after the press machine is started, the inner cross beam of the press machine can drive the extrusion rod to move downwards in the vertical through hole, so that the blank is reversely extruded, and an outer cross beam of the press machine can drive the inner concave die to slide up and down and be positioned at a forming position; the utility model discloses a light alloy pipe material forming die, including outer die, elasticity ejecting mechanism, extrusion pole, elasticity ejecting mechanism, the extrusion pole is down when pushing the blank, elasticity ejecting mechanism one end is arranged in outer die and is supported with tubular product shaping chamber, and the other end is fixed on the membrane seat of outer die below, elasticity ejecting mechanism has elasticity, and when the extrusion pole was down to the blank extrusion, elasticity ejecting mechanism is by compression deformation after the extrusion, and the in-process that elasticity ejecting mechanism replied initial condition when the extrusion pole return stroke, upwards jacking is ejecting from tubular product shaping intracavity with the light alloy tubular product after the shaping. Therefore, the arranged concave die can be used for placing blanks and playing a role of the charging barrel, and can also be used for enabling the extrusion rod to slide up and down to provide an extrusion path. The vertical through hole in the inner concave die is communicated with the cavity of the outer concave die, so that the blank can enter the cavity of the outer concave die through the vertical through hole after being extruded by the extrusion rod, firstly passes through the lower end of the pipe forming cavity and then continuously flows upwards until being formed. The forming part is designed into a pipe forming cavity consisting of an inner concave die and an outer concave die, and the blank is placed in the inner concave die, so that the forming is more convenient, and the forming manufacturability is improved. The elastic ejecting piece mechanism can store energy in the backward extrusion process, releases the energy after the backward extrusion is finished, and ejects the formed light alloy pipe fitting through reverse elasticity, so that the automatic demolding of the die is effectively improved, and the automation degree of the die is improved.

Furthermore, a heating device for heating the outer female die and the blank is also arranged in the outer female die and close to the cavity of the outer female die. Like this, the heating device who sets up can heat external die and blank, and this kind of heating mode compares traditional external heating back, puts the blank in the mould, and is better to the control of temperature, and is more accurate, all has great promotion to the manufacturability of taking shape and the high performance nature of finished piece.

Furthermore, the heating device is a heating coil which can be electrically connected with an external power supply, an annular groove is formed in the middle of the outer female die, and the heating coil is arranged in the annular groove. Like this, the mode heating through heating coil heating is fast, and because heating coil assembles in the annular groove of outer die, its and the outer die between area of contact is great, can effectively shorten the heating time.

Further, heating device still includes a heating rod that can be connected with external power source electricity, and through the switch on power supply, the heating rod can be to the heating of external die to make on the heat transmits the blank through the interior concave mould, heat the blank. Therefore, the arranged heating rod can also heat the external female die, the heating rod can be used with the heating coil in an interaction manner, the production efficiency of the pipe is improved, and the production period is shortened.

Further, still be equipped with a temperature sensor who is used for real-time supervision and takes notes outer die temperature in outer die, still be equipped with one and pass through the temperature control device that the electric wire is connected with heating coil and heating rod on one side of outer die, temperature control device is connected through wired or wireless mode with temperature sensor, is equipped with a power source head of putting through with external power supply on temperature control device. Like this, temperature sensor can detect the real-time temperature information of outer die to transmit this temperature data to temperature control device, temperature control device is after receiving the real-time temperature data of outer die, can control the temperature that heating rod and heating coil output through the size of control heating rod and heating coil electric current, and then the temperature and the time of accurate control blank heating.

Furthermore, the elastic ejecting mechanism comprises an ejecting block, a plurality of ejector rods are fixedly arranged below the ejecting block, an elastic element is fixed at the lower ends of the ejector rods, and the elastic element is arranged below the outer female die; the ejector piece block is a disc with the diameter equal to or smaller than the diameter of the bottom of the cavity of the outer female die, the ejector rod is vertically arranged, the lower end of the ejector rod is extruded outside the outer female die after the ejector piece block and the ejector rod receive extrusion force applied by the extrusion rod, the extrusion force is transmitted to the elastic element, and therefore the elastic element is compressed and deformed. Like this, the ejector pin can extrude elastic element, and the ejector pin stretches out outer die lower extreme after, elastic element and outer die lower extreme have certain distance to extrusion tension for elastic element provides certain space. After the ejecting piece block and the ejector rod are extruded, the ejecting piece block is embedded in the outer concave die, so that no displacement space exists, and displacement cannot occur. And the ejector pin is receiving the extrusion of decurrent back, and the lower extreme forms certain extrusion to elastic element to make its deformation compression, after the extrusion stem return stroke, the ejector pin no longer receives decurrent extrusion force, and at this moment, elastic element can upwards jack at the recovery in-process promptly, thereby ejecting the finished piece. The mode of ejecting through elasticity can not cause the waste to the energy, and long service life has fine practicality.

Furthermore, one side of the outer concave die is also provided with a cavity for introducing CO into the tube forming cavity₂CO of₂Shielding gas means, said CO₂The shielding gas device comprises at least one CO₂One end of the gas pipe is communicated with the pipe forming cavity, and the other end of the gas pipe is communicated with the CO₂The gas tank is communicated with the gas tank, and a pressure gauge and a direction regulating valve are arranged on the gas pipe. Therefore, in the hot extrusion process, the light alloy pipe is extremely easy to oxidize, and meanwhile, when the light alloy pipe is formed, the blank also can release certain heat to damage the formed pipe to a certain extent, and CO is introduced₂After the protective gas is used, the oxidation of the pipe can be prevented to a certain extent and the temperature of the surface of the pipe can be reduced.

Furthermore, the included angle between the upper sizing area and the lower reducing shearing area is 130-150 degrees. Therefore, more strain can be accumulated in the process of backward extrusion of the blank, so that the crystal grains of the formed pipe can be refined, and the pipe cannot be cracked due to the overlarge angle.

A forming method for preparing high-performance ultra-fine grain light alloy pipes comprises the following steps: s1, homogenizing the blank; s2, placing the homogenized blank into a mold for heating pretreatment, wherein the mold is as described above, the blank is in a bar shape and is placed in the vertical through hole of the inner concave mold, and the blank is heated by a heating device in the outer concave mold; s3, after the blank is heated to the forming temperature, starting a press machine, enabling an outer beam of the press machine to drive an inner concave die to move downwards to a forming position for fixing, then enabling an inner beam of the press machine to drive an extrusion rod to move downwards and reversely extrude a blank piece placed in a vertical through hole of the inner concave die, and continuously extruding the blank in the process of reverse extrusion until the whole tube forming cavity is filled with the blank to form the light alloy tube; and S4, after the backward extrusion is finished, the inner beam of the press drives the extrusion rod to move upwards, then the outer beam drives the inner concave die to move upwards, and the elastic jacking part mechanism jacks the molded light alloy pipe while the inner concave die moves upwards, so that the light alloy pipe is pushed out of the pipe molding cavity. Therefore, when the billet is subjected to backward extrusion, the contact force between the metal billet and the die is reduced, the downward flowing resistance of the billet is relatively reduced, the required extrusion force is reduced, and the energy consumption is reduced; by means of backward extrusion, the blank is deformed more greatly, more strain is accumulated, the dynamic recrystallization degree of the forming is favorably increased, and grains are refined. During back extrusion, the metal flow is concentrated primarily near the die orifice, so that the metal deformation is more uniform along the length of the tube in the direction of the deformation. In another aspect, the tube forming cavity is composed of an upper sizing area and a lower reducing shearing area, when a blank passes through the reducing shearing area, the blank generates shearing deformation, the shearing deformation can weaken the dominant position of the basal plane texture of the tube and generate tilting, the microstructure of the thin-wall tube and the form of a second phase in a matrix are greatly improved, the surface and core tissues are refined, and the banded tissues are reduced or even eliminated. The second phase is dispersed, fine and round in distribution in a new deformation mode. The procedures of backward extrusion, backward extrusion shearing and the like of the method can effectively promote the generation of dynamic recrystallization of the alloy and homogenize the structure of the product. The finally obtained pipe has a compact and uniform structure, the defect rate of internal holes is low, the probability of cracks generated on the pipe under a large strain condition is reduced, the energy consumption is reduced, the cost is reduced, and the energy is saved.

Further, in S3, when the extrusion rod is reversely extruded, the extrusion speed is 1-5mm/S, and the extrusion temperature required by the blank is 360-430 ℃ during reverse extrusion. Thus, the temperature range is above the recrystallization temperature of many light alloys such as magnesium alloy and aluminum alloy, so that dynamic recrystallization can be generated in the forming process, the size of crystal grains is changed, a plurality of equiaxed fine grains are formed, and the strength and the plasticity of the product are improved. The selection of the speed interval value can well ensure the surface quality of the pipe, the service life of the die can be shortened at an overhigh speed, and the surface quality of the pipe can be damaged at an overlow speed.

Drawings

FIG. 1 is a view showing a structure of a billet in a die when an extrusion stem is extruded downward in the embodiment;

FIG. 2 is a flow process diagram of the billet being extruded in the embodiment;

FIG. 3 is an equivalent strain diagram of the billet just after the billet is subjected to reverse extrusion forming in the embodiment;

FIG. 4 is an equivalent strain diagram of the billet just after passing through the lower reducing shear zone in the example;

FIG. 5 is an equivalent strain diagram of the billet just after extrusion into the upper gauge in the example;

FIG. 6 is an equivalent strain diagram of the embodiment when the billet is fast extruded to the top of the tube forming cavity;

FIG. 7 is a graph showing the metal flow rate of the billet immediately after the backward extrusion molding in the example;

FIG. 8 is a graph of the metal flow rate just after the billet passes through the lower variable diameter shear zone in the example;

FIG. 9 is a graph of the metal flow rate of the billet just after extrusion into the upper gauge in the example;

FIG. 10 is a graph of the metal flow rate as the billet is being extruded into the top of the tube forming cavity in the example;

FIG. 11 is an enlarged schematic view of a microstructure of a magnesium alloy before entering a shearing section for shearing and forming by using a die in the embodiment;

FIG. 12 is an enlarged schematic view of the microstructure of the magnesium alloy after shear forming in the shear zone by the die in the example.

In the figure: the device comprises an extrusion rod 1, an inner concave die 2, a vertical through hole 21, an outer concave die 3, an annular groove 31, a pipe forming cavity 4, an upper sizing area 41, a lower reducing shearing area 42, a heating device 5, a heating coil 51, a heating rod 52, a temperature sensor 6, an elastic ejecting part mechanism 7, an ejecting part block 71, an ejector rod 72, an elastic element 73, a blank 8, a temperature control device 9, CO₂Shielding gas device 10, CO₂The device comprises a gas tank 101, a gas pipe 102, a pressure gauge 103, a direction regulating valve 104 and a protection cabinet 105.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

Example (b):

the mold and the molding method for preparing the high-performance ultrafine-grained light alloy pipe provided by the embodiment comprise an extrusion rod 1, a female mold and an elastic ejector mechanism 7; the die comprises an inner die 2 and an outer die 3, a vertical through hole 21 for containing a blank to be processed is arranged in the middle of the inner die 2, a cavity with the shape and size consistent with the shape and outer diameter of a light alloy pipe to be prepared is arranged in the middle of the outer die 3, the upper end of the inner die 2 is fixedly arranged on an outer cross beam of a press, the lower end of the inner die is arranged in the cavity of the outer die 3 and is coaxial with the outer die 3, the outer end surface of the inner die 2 is consistent with the shape and inner diameter of the light alloy pipe to be prepared, a pipe forming cavity 4 is formed between the outer end surface of the inner die and the cavity of the outer die, the pipe forming cavity 4 consists of an upper sizing area 41 and a lower reducing shearing area 42, and the pipe cavity 4 is communicated with the vertical through hole 21; one end of the extrusion rod 1 is fixedly arranged on an inner cross beam of the press machine, the other end of the extrusion rod is arranged in a vertical through hole 21 of the inner concave die 2, after the press machine is started, the inner cross beam of the press machine can drive the extrusion rod 1 to move downwards in the vertical through hole to realize backward extrusion of a blank, and an outer cross beam of the press machine can drive the inner concave die 2 to slide up and down and be positioned at a forming position; the utility model discloses a light alloy pipe material extrusion die, including outer die, elasticity ejecting mechanism 7, extrusion pole 1, elasticity ejecting mechanism 7 one end is arranged in outer die and is supported with tubular product shaping chamber, and the other end is fixed on the membrane seat of outer die below, elasticity ejecting mechanism 7 has elasticity, and when extrusion pole 1 descends to blank 8 extrusion, elasticity ejecting mechanism is by extrusion back compression deformation, and elasticity ejecting mechanism replies the in-process of initial condition when the extrusion pole return stroke, upwards the jacking, light alloy tubular product after will shaping is ejecting from tubular product shaping intracavity.

And a heating device 5 for heating the outer concave die 3 and the blank 8 is also arranged in the outer concave die 3 and close to the cavity of the outer concave die. The heating device is a heating coil 51 which can be electrically connected with an external power supply, an annular groove 31 is arranged in the middle of the outer female die 3, and the heating coil 51 is arranged in the annular groove 31. For further increasing heating efficiency, heating device still includes a heating rod 52 that can be connected with external power source electricity, and through the switch on power supply, heating rod 52 can be to the heating of external die to make the heat pass through the indent mould and transmit on the blank, heat the blank.

Still be equipped with a temperature sensor 6 that is used for real-time supervision and takes notes outer die temperature in outer die, still be equipped with one and pass through the temperature control device 9 that the electric wire is connected with heating coil 51 and heating rod 52 on one side of outer die, temperature control device 9 is connected through wired or wireless mode with temperature sensor 6, is equipped with a power source head of putting through with external power supply on temperature control device 9.

The elastic ejecting part mechanism 7 comprises an ejecting part block 71, a plurality of ejector rods 72 are fixedly arranged below the ejecting part block 71, an elastic element 73 is fixed at the lower ends of the ejector rods 72, and the elastic element 73 is arranged below the outer female die 3; ejecting piece block 72 is a disc that the diameter equals or is less than the cavity bottom diameter of outer die 3 with the cavity bottom diameter of a diameter, the ejector pin is vertical setting, ejecting piece block 71 and ejector pin 72 are behind the extrusion force that receives the extrusion stem and applys, and ejector pin 72 lower extreme is outside being extruded outer die to on transmitting this extrusion force to elastic element 73, thereby make elastic element by compression deformation, when the extrusion stem is accomplished to extrude and the return stroke, elastic element no longer receives outside extrusion, upwards bounce-back to drive ejector pin and ejecting piece block move up, light alloy tubular product after will shaping is ejecting from tubular product shaping intracavity. During assembly, the lower end of the elastic element is abutted against the lower main body part of the hydraulic device. The elastic element 73 is made of rubber, and the compression strength can reach 160-100 Mpa. Therefore, the elastic element has large elasticity and can bear multiple times of extrusion, and the elasticity cannot be reduced after the multiple times of extrusion.

One side of the outer concave die is also provided with a cavity for leading CO into the pipe forming cavity 4_{2 of}CO₂Shielding gas means 10, said CO₂The shielding gas device 10 comprises two intercommunicated CO₂The gas tank 101 and a gas pipe 102, one end of the gas pipe 102 is communicated with the pipe forming cavity 4, and the other end is communicated with the CO₂The gas tank is communicated, and a pressure gauge 103 and a direction regulating valve 104 are arranged on the gas conveying pipe 102. As shown, in this embodiment, two COs₂The gas tank 101 is arranged in a protective cabinet 105, and the gas pipe 102 and CO are arranged in the protective cabinet₂When the gas tank 101 is communicated, the gas tank needs to pass through the protective cabinet 105 and then is communicated with CO₂The gas tank 101 communicates. To make the whole gas filledThe pipe forming cavity 4, in this application the gas pipe 102, is preferably located at the lower end of the pipe forming cavity 4 and near the bottom of the ground.

In order to better control the pressing-down speed of the extrusion rod 1, the pressing-down pressure of the extrusion rod 1 is effectively controlled before the blank of the light alloy pipe made of one material is pressed down, so that the forming quality of the pipe is ensured. The hydraulic machine of the embodiment is also provided with a pressure sensor which is connected with the pressure recorder 16 through a lead, the design can record a real-time pressure value during forming, and the descending speed of the hydraulic machine is adjusted through the pressure value borne by the blank (if the pressure load displayed on the recorder is overlarge, the running speed of the hydraulic machine can be properly reduced), so that the forming manufacturability is improved, and the service life of the device is influenced to a certain extent and the forming performance of the pipe is reduced due to the overlarge pressure load during blank forming.

In the embodiment, the included angle between the upper sizing area 41 and the lower reducing shearing area 42 is 130-150 degrees. As shown in the figure, the lower diameter-variable shearing zone and the upper diameter-fixed zone in the embodiment are connected through a fillet as a smooth transition.

Furthermore, the vertical through hole in the middle of the inner concave die 2 and the cavity of the outer concave die are coaxial. Therefore, the pipe forming cavity formed by the inner concave die and the outer concave die can be coaxial with the concave die, and the thickness of the prepared pipe is consistent.

A forming method for preparing high-performance ultra-fine grain light alloy pipes comprises the following steps: s1, homogenizing the blank 8 (specifically, putting the blank into a muffle furnace, heating to 400 ℃, preserving heat for 3-4 hours, and then cooling along with the furnace); s2, placing the homogenized blank 8 into a mold for heating pretreatment, wherein the mold is as described above, the blank is in a bar shape and is placed in the vertical through hole of the inner concave mold, and the blank is heated by a heating device in the outer concave mold; s3, after the blank is heated to the forming temperature, starting a press machine, enabling an outer beam of the press machine to drive an inner concave die to move downwards to a forming position for fixing, then enabling an inner beam of the press machine to drive an extrusion rod to move downwards and reversely extrude a blank piece placed in a vertical through hole of the inner concave die, and continuously extruding the blank in the process of reverse extrusion until the whole tube forming cavity is filled with the blank to form the light alloy tube; and S4, after the backward extrusion is finished, the inner beam of the press drives the extrusion rod to move upwards, then the outer beam drives the inner concave die to move upwards, and the elastic jacking part mechanism jacks the molded light alloy pipe while the inner concave die moves upwards, so that the light alloy pipe is pushed out of the pipe molding cavity.

In S3, when the extrusion rod is reversely extruded, the extrusion speed is 1-5mm/S, and the extrusion temperature required by the blank is 360-430 ℃.

In S3, the extrusion rod extrudes the blank reversely and simultaneously opens CO₂A directional control valve 11 in the protective gas device 10, in which case CO₂The gas flows into the pipe forming cavity 4 through the gas conveying pipe 102 and fills the pipe forming cavity 4, so that the pipe is oxidized in the extrusion process of the blank and the temperature of the surface of the pipe is reduced.

Fig. 2 is a process of forming a finite element simulated blank, wherein the blank firstly flows through the bottom of an outer female die, namely diffuses towards the periphery, then flows upwards and sequentially passes through a backward extrusion shearing area, and finally is formed.

Fig. 3-6 are equivalent strain diagrams during the blank forming process, and fig. 3 is an equivalent strain diagram of the blank immediately after the reverse extrusion forming, wherein the equivalent strain at the time is smaller, and the strain value at the corner is larger than that at other parts. Fig. 4 is a strain diagram of the billet just after passing through the backward extrusion shearing area, and it can be seen from the diagram that the strain value of the shearing section is obviously larger than that of the rest part, and the addition of the shearing section obviously accumulates strain when being combined with fig. 2, namely the billet finishes the backward extrusion shearing. Meanwhile, it is obvious from the equivalent strain process of fig. 3-6 that the strain value of the area near the shearing section is the largest, the equivalent strain amount and the distribution thereof are key factors influencing the refinement and uniformity of the crystal grains of the formed pipe, the larger strain amount can increase the dislocation density in the crystal grains, aggravate the lattice distortion and provide a large number of crystal nuclei for dynamic recrystallization, the microstructure diagram before the shearing and forming of the magnesium alloy shearing section by using the die shown in fig. 11 is shown, fig. 12 is the microstructure after the shearing and forming of the magnesium alloy shearing section, and it is clear from the two microstructure diagrams that the crystal grains are larger before the shearing section is added and the crystal grains are refined by the addition of the shearing section.

Fig. 7 to 10 are graphs of the metal flow rate after the billet is extruded to different positions in the examples.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the technical solutions, and although the present invention has been described in detail by referring to the preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention can be made without departing from the spirit and scope of the technical solutions, and all the modifications and equivalent substitutions should be covered by the claims of the present invention.

Claims (5)

1. A mould for preparing high-performance and ultra-fine grain light alloy pipes comprises an extrusion rod (1), a female die and an elastic ejector mechanism (7), and is characterized in that the female die consists of an inner female die (2) and an outer female die (3), a vertical through hole (21) for accommodating a blank to be processed is arranged in the middle of the inner female die (2), a cavity with the shape and size consistent with the shape and outer diameter of the light alloy pipe to be prepared is arranged in the middle of the outer female die (3), the upper end of the inner female die (2) is fixedly arranged on an outer cross beam of a press machine, and a gap is reserved between the upper end of the inner female die and the upper end of the outer female die (3); the lower end of the inner female die (2) is arranged in a cavity of the outer female die (3) and is coaxial with the outer female die (3), the outer end surface of the lower end of the inner female die (2) is consistent with the shape and the inner diameter of a light alloy pipe to be prepared, a pipe forming cavity (4) is formed between the outer end surface of the lower end of the inner female die and the cavity of the outer female die, the pipe forming cavity (4) is composed of an upper sizing area (41) and a lower reducing shearing area (42), the pipe forming cavity (4) is communicated with the vertical through hole (21), and the included angle between the upper sizing area and the lower reducing shearing area is 130-150 degrees; one end of the extrusion rod (1) is fixedly installed on an inner cross beam of the press machine, the other end of the extrusion rod is arranged in a vertical through hole (21) of the inner concave die (2), after the press machine is started, the inner cross beam of the press machine can drive the extrusion rod (1) to move downwards in the vertical through hole, backward extrusion of blanks is achieved, and an outer cross beam of the press machine can drive the inner concave die (2) to slide upwards and downwardsMoving and positioning at a forming position; one end of the elastic jacking part mechanism (7) is arranged in the outer female die and is abutted against the pipe forming cavity, the other end of the elastic jacking part mechanism is fixed on the film seat below the outer female die, the elastic jacking part mechanism has elasticity, when the extrusion rod descends to extrude a blank, the elastic jacking part mechanism is extruded and then compressed and deformed, when the extrusion rod returns, the elastic jacking part mechanism is upwards jacked in the process of returning to the initial state, and the formed light alloy pipe is jacked out of the pipe forming cavity; the elastic ejecting mechanism (7) comprises an ejecting block (71), a plurality of ejector rods (72) are fixedly arranged below the ejecting block (71), an elastic element (73) is fixed at the lower ends of the ejector rods, the elastic element is arranged below the outer female die (3), is made of rubber and has the compressive strength of 160-100 Mpa; the ejecting piece block (72) is a disc with the diameter equal to or smaller than the diameter of the bottom of a cavity of the outer female die (3), the ejector rod (72) is vertically arranged, after the ejecting piece block (71) and the ejector rod (72) are subjected to extrusion force exerted by the extrusion rod, the lower end of the ejector rod (72) is extruded outside the outer female die (3) and the extrusion force is transmitted to the elastic element (73), so that the elastic element (73) is compressed and deformed, when the extrusion rod (1) completes extrusion and return stroke, the elastic element (73) is not subjected to external extrusion any more, rebounds upwards, drives the ejector rod and the ejecting piece block to move upwards, and ejects the molded light alloy pipe from the pipe molding cavity; one side of the outer concave die is also provided with a cavity for leading CO into the pipe forming cavity (4)₂CO of₂Shielding gas means (10), said CO₂The shielding gas device (10) comprises at least one CO₂The gas tank (101) and a gas pipe (102), one end of the gas pipe (102) is communicated with the pipe forming cavity (4), and the other end of the gas pipe (102) is communicated with CO₂The gas tank (101) is communicated, and a pressure gauge (103) and a direction regulating valve (104) are arranged on the gas transmission pipe (102); a heating device (5) for heating the outer concave die (3) and the blank (8) is also arranged in the outer concave die (3) and close to the cavity of the outer concave die; the heating device (5) is a heating coil (51) which can be electrically connected with an external power supply, an annular groove (31) is arranged in the middle of the outer concave die (3),the heating coil (51) is arranged in the annular groove (31).

2. The mold for manufacturing high-performance ultra-fine grain light alloy tubing according to claim 1, wherein the heating device further comprises a heating rod (52) electrically connected to an external power source, and the heating rod (52) heats the outer female mold by connecting the power source, so that heat is transferred to the billet through the inner female mold to heat the billet.

3. The die for preparing high-performance ultra-fine grain light alloy tubing according to claim 1 or 2, characterized in that a temperature sensor (6) for monitoring and recording the temperature of the outer female die in real time is further provided in the outer female die, a temperature control device (9) electrically connected with the heating coil (51) and the heating rod (52) through electric wires is further provided at one side of the outer female die, the temperature control device (9) is connected with the temperature sensor (6) in a wired or wireless manner, and a power source head connected with an external power supply is provided on the temperature control device (9).

4. A forming method for preparing high-performance ultra-fine grain light alloy pipes comprises the following steps: s1, homogenizing the blank (8); s2, placing the homogenized blank (8) into a mold for heating pretreatment, wherein the mold is as set forth in any one of claims 1-3, the blank is in a bar shape and is placed in a vertical through hole of an inner concave mold; s3, after the blank is heated to the forming temperature, starting a press machine, enabling an outer beam of the press machine to drive an inner concave die to move downwards to a forming position for fixing, then enabling an inner beam of the press machine to drive an extrusion rod to move downwards and reversely extrude a blank piece placed in a vertical through hole of the inner concave die, and continuously extruding the blank in the process of reverse extrusion until the whole tube forming cavity is filled with the blank to form the light alloy tube; and S4, after the backward extrusion is finished, the inner beam of the press drives the extrusion rod to move upwards, then the outer beam drives the inner concave die to move upwards, and the elastic jacking part mechanism jacks the molded light alloy pipe while the inner concave die moves upwards, so that the light alloy pipe is pushed out of the pipe molding cavity.

5. The forming method of claim 4, wherein in S3, the extrusion speed is 1-5mm/S when the extrusion rod is backward extruded, and the extrusion temperature required by the billet during backward extrusion is 360-430 ℃.

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