CN101015841A - Warm static liquid extrusion method and mould for producing magnesium alloy wire or bar - Google Patents

Abstract

The invention relates to a method for manufacturing magnesium alloy wire or rod by thermostatic extrusion and an extrusion die thereof, which relates to a method for manufacturing magnesium alloy wire or rod by thermostatic extrusion and a special extrusion die for the method. The invention effectively solves the problems of poor plasticity, large flow friction resistance, easy cracks and high processing cost during the plastic processing of the magnesium alloy. The specific steps of the method include: magnesium alloy billet processing, lubricant coating, castor oil heating, warm static liquid extrusion die heating and temperature control, magnesium alloy billet injection, castor oil injection, movable punch release, pressurization, extrusion take shape. Magnesium alloy wire or bar thermostatic extrusion die comprises movable punch (26), and movable punch (26) is placed directly below punch (6) and is coaxial with punch (6), and movable punch The lower end of (26) passes through the punch through hole (8) provided in the middle of the die platen (17) and is installed on the upper part of the extrusion cylinder (13). The extrusion cylinder (13) is a multi-layer cold-pressed Combination extrusion barrel. The wires and rods produced by the method and the special mold have higher mechanical properties and better surface quality, and the specific strength and specific stiffness indexes are also improved.

Description

Magnesium alloy wire or rod thermostatic extrusion manufacturing method and extrusion die

technical field

The invention relates to a method for manufacturing magnesium alloy wire or rod by thermostatic liquid extrusion and a special extrusion die for the method.

Background technique

Magnesium alloy is currently the lightest engineering metal material, its density is about 1.78g/cm ³ , which is 1/4 of steel, 2/3 of aluminum, and 1/4 of zinc. Due to the low density, compared with commonly used engineering materials, the specific strength and specific stiffness of magnesium alloys are much higher. In addition, magnesium alloy also has excellent thermal conductivity, vibration absorption and wear resistance, good electromagnetic shielding performance, and is easy to cast and machine. At the same time, magnesium alloy is also a reusable and environmentally friendly material. Due to these remarkable advantages, magnesium alloys are increasingly widely used in industrial fields such as automobiles, aerospace, and information communications. From the perspective of light weight, magnesium alloy is often used to replace steel and aluminum alloy parts with large specific gravity; from the perspective of improving strength and environmental protection, it is also used to replace engineering plastics and wood. The annual consumption of magnesium alloys is now growing rapidly at a rate of 15%, much higher than the growth rate of steel, aluminum, copper, nickel and zinc.

At present, magnesium alloy forming processing in engineering mainly adopts casting processing technologies such as die casting, semi-solid forming and thixoforming. More than 90% of magnesium alloy products worldwide are castings, and less than 5% of products are processed by metal plastic deformation. . Due to the immaturity of plastic processing technology, the popularization and application of magnesium alloy structural parts has been greatly restricted, especially the production of magnesium alloy wire and rod. Magnesium alloy is a metal material with poor plasticity at room temperature. There are several major difficulties in its plastic processing: the crystal structure of magnesium alloy is a close-packed hexagonal lattice, and there are only three slip systems in one slip plane. The shift system makes the plasticity of magnesium alloy at room temperature very poor; the surface friction coefficient of magnesium alloy is large at high temperature, and its flow friction resistance is relatively large during plastic processing; the thermal conductivity of magnesium alloy is good, and it is easy to contact the mold when performing warm or thermoplastic processing. Chilling causes cracks; high-temperature magnesium alloys will be oxidized violently in the air, so additives such as flame retardants must be used, which will greatly increase the production cost of plastic processing of magnesium alloys. Due to the above problems, the application of plastically processed products of magnesium alloys has been greatly restricted.

Contents of the invention

The invention solves the problems of poor plasticity, large flow friction resistance, easy cracks and high processing cost during the plastic processing of the magnesium alloy.

The technical scheme of the magnesium alloy wire or bar thermostatic extrusion manufacturing method is realized according to the following steps: 1. Magnesium alloy billet processing: select the magnesium alloy bar stock, and process the magnesium alloy bar stock head into a cone angle of 20 ~ 60° conical surface; 2. Apply lubricant: mix castor oil and graphite in a ratio of 3 to 5:1 by weight and apply it on the surface of the processed magnesium alloy blank; 3. Heating castor oil: Preheat castor oil Heat to 250-300°C; 4. Heating and temperature control of the warm-static liquid extrusion die: heat the warm-static liquid extrusion die to 250-300°C and control the temperature between 250-300°C; 5. Put magnesium alloy Billet: Put the magnesium alloy billet completed in step 2 into the extrusion die of a warm-static liquid extrusion die at a temperature of 250-300°C. The conical head of the magnesium alloy billet matches the conical surface of the extrusion die mouth, The hydrostatic extrusion die directly heats the billet, so that the temperature of the magnesium alloy billet reaches 250-300°C; 6. Castor oil injection: inject castor oil with a temperature of 250-300°C into the extrusion die of the hydrostatic extrusion die 7. Put the movable punch: put the lower end of the movable punch into the upper part of the inner cavity of the extrusion cylinder; 8. Pressurize: pressurize the movable punch, and control the extrusion temperature of the magnesium alloy billet at 250-300°C 9. Extrusion forming: After the movable punch completes the extrusion stroke, the magnesium alloy wire or rod formed by warm and static liquid extrusion is extruded from the extrusion nozzle.

The realization of the above-mentioned manufacturing method must be realized with the help of a magnesium alloy wire or rod thermostatic extrusion die, which includes an upper plate, a punch fixing sleeve, a punch pad, a punch, an extrusion cylinder, Die platen, extrusion die, spacer, mold base cover, mold base, armored thermocouple, temperature controller, electric heating tube, wires and wires, the upper template is placed on the upper end of the punch fixed sleeve and The fixed sleeve is connected, the punch pad is placed in the cylindrical hole provided in the punch fixed sleeve, and the upper end of the punch is placed in the conical hole provided in the punch fixed sleeve. The cylindrical hole and the conical hole are connected. The seat cover, spacer, extrusion cylinder, and die platen are placed in order from bottom to top, the extrusion die is placed above the bottom cushion block in the extrusion cylinder, the die platen, die base cover It is fixedly connected with the mold base, and the electric heating tube is installed in the electric heating tube hole in the extrusion cylinder. The electric heating tube is electrically connected to the temperature controller through the wire, and the temperature controller is electrically connected to the armored thermocouple through the wire. It also includes a movable punch , the movable punch is placed directly below the punch and coaxial with the punch, the lower end of the movable punch passes through the punch through hole provided in the middle of the die platen and is installed in the upper part of the extrusion barrel, the said The extruded barrel is a multi-layer cold-pressed combined extruded barrel.

The thermostatic extrusion manufacturing method of magnesium alloy wire or rod can make the magnesium alloy billet with poor plasticity at room temperature always in the state of three-way hydrostatic pressure during the deformation process, so that the plasticity is significantly improved; the appropriate temperature also further improves the magnesium alloy. The plasticity of the alloy billet reduces the resistance to plastic deformation; castor oil is both a liquid pressure medium and a lubricant, forming a liquid isolation and hydrodynamic lubrication between the workpiece and the mold, which greatly reduces the frictional resistance of metal flow; the liquid pressure medium also avoids The direct contact between the magnesium alloy and the mold greatly reduces the heat dissipation speed of the magnesium alloy and avoids the generation of cracks on the surface of the workpiece; the liquid pressure medium isolates the magnesium alloy from the air, which greatly reduces the degree of oxidation of the high-temperature magnesium alloy; Extrusion can also obtain fine grain structure, and hydrostatic high pressure can also reduce or even eliminate micro-crack defects inside the billet. Compared with traditional methods such as extrusion, drawing, rolling, etc., the wires and rods produced by this method have higher mechanical properties, better surface quality, and a great improvement in specific strength and specific stiffness. improve. It is an ideal material to replace steel and aluminum alloy parts, and is very suitable for the manufacture of mechanical parts in the fields of aviation, aerospace, automobiles, motorcycles, electric vehicles, bicycles and baby carriages. Magnesium alloy wire or rod thermostatic extrusion die adopts multi-layer cold pressing combined extrusion cylinder and sealing structure, which greatly improves the pressure of magnesium alloy wire or rod thermostatic extrusion, and the temperature control device ensures the temperature The hydrostatic extrusion temperature and the use of the movable punch have realized the hydrostatic extrusion without the use of guide pillars and guide sleeves.

Description of drawings

Figure 1 is a cross-sectional view of a magnesium alloy wire or rod thermostatic extrusion die, Figure 2 is a structural diagram of a multi-layer cold-press combined extrusion barrel before press-fitting, and Figure 3 is a multi-layer cold-press combined extrusion barrel press-fit Rear structural diagram; Fig. 4 is an enlarged view of the upper sealing structure of the extrusion barrel; Fig. 5 is an enlarged view of the lower sealing structure of the extrusion barrel; Fig. 6 is a view of the magnesium alloy billet.

Detailed ways

Specific embodiment one: a kind of magnesium alloy wire or bar material thermostatic extrusion manufacturing method described in this embodiment, it is realized according to the following steps: 1, magnesium alloy billet processing: choose magnesium alloy bar stock, Process the magnesium alloy bar head into a conical surface with a cone angle of 20-60°; 2. Apply lubricant: mix castor oil and graphite in a weight ratio of 3-5:1 and apply it to the processed magnesium alloy blank On the surface; 3. Castor oil heating: preheat the castor oil to 250-300°C; 4. Heating and temperature control of the warm static liquid extrusion die: heat the warm static liquid extrusion die to 250-300°C and control the temperature Between 250 and 300°C; 5. Put the magnesium alloy billet: put the magnesium alloy billet that has completed step 2 into the extrusion die of a warm and static liquid extrusion die with a temperature of 250 to 300°C. The head and the conical surface of the extrusion die are matched, and the billet is directly heated through the hydrostatic extrusion die, so that the temperature of the magnesium alloy billet reaches 250-300°C; Inject into the inner cavity of the extrusion die of the warm and static liquid extrusion die; 7. Put the movable punch: put the lower end of the movable punch into the upper part of the inner cavity of the extrusion cylinder; 8. Pressurize: pressurize the movable punch , The extrusion temperature of the magnesium alloy billet is controlled at 250-300°C; 9. Extrusion forming: After the movable punch completes the extrusion stroke, the magnesium alloy wire or rod formed by warm and static liquid extrusion starts from the extrusion nozzle. Extruded.

Embodiment 2: The difference between this embodiment and Embodiment 1 is that the magnesium alloy billet is first heated to 250-300°C, and the heating rate is kept at 6-8°C/min. After reaching the heating temperature, the billet must be heated The furnace is kept warm for at least 15-45 minutes, and then the heated magnesium alloy billet is put into the inner cavity of the extrusion die of the hydrostatic extrusion die. Using such process steps can greatly improve production efficiency.

Specific embodiment three: the difference between this embodiment and specific embodiment one is that in step one, the magnesium alloy bar head is processed into a conical surface with a cone angle α of 38°, and a cone with a cone angle γ of the extrusion die mouth of 40° The surfaces cooperate to form an effective seal.

Embodiment 4: The difference between this embodiment and Embodiment 1 is that in step 2, castor oil and graphite are mixed in a ratio of 4:1 by weight to prepare a lubricant, and the lubricating effect is the best.

Embodiment 5: This embodiment differs from Embodiment 1 in that the temperature of the hydrostatic extrusion die in step 4 is controlled at 270° C., which is easier to control.

Embodiment 6: This embodiment differs from Embodiment 1 in that the moving speed of the movable punch in step 8 is 5-15 mm/s, which effectively ensures the extrusion effect.

Specific embodiment seven: as shown in accompanying drawing 1 magnesium alloy wire material or bar thermostatic liquid extrusion die, it is made up of upper template 1, punch fixing sleeve 2, punch pad 5, punch 6, extrude Tube 13, die platen 17, extrusion die 18, spacer 19, die base cover plate 20, die base 21, armored thermocouple 31, temperature controller 29, electric heating tube 28 and wire 30, wire 34 and movable The punch is composed of 26, the upper template 1 is placed on the upper end of the punch fixing sleeve 2 and connected with the punch fixing sleeve 2, the punch cushion block 5 is placed in the cylindrical hole 3 provided in the punch fixing sleeve 2, and the punch 6 The upper end of the upper end of the punch is placed in the conical hole 4 provided in the punch fixing sleeve 2. The cylindrical hole 3 and the conical hole 4 are connected. Place the extrusion die 18 above the bottom cushion block 19 in the extrusion cylinder 13, the die pressing plate 17, the die base cover plate 20 and the die base 21 are fixedly connected, and the electric heating tube 28 is installed. In the electric heating pipe hole 7 in the extrusion cylinder 13, the electric heating pipe 28 is electrically connected to the temperature controller 29 through the wire 34, and the temperature controller 29 is electrically connected to the armored thermocouple 31 through the wire 30. The movable punch 26 Placed directly below the punch 6 and coaxial with the punch 6, the lower end of the movable punch 26 passes through the punch through hole 8 provided in the middle of the die platen 17 and is installed in the upper part of the extrusion cylinder 13. The extruding cylinder 13 is a multi-layer cold pressing combined extruding cylinder. When the magnesium alloy wire or bar thermostatic extrusion die is in working condition, the upper platen 1 is connected to the hydraulic press slider 32, the mold base 21 is fixedly installed on the workbench 33, and the magnesium alloy billet 14 is placed in the extrusion cylinder 13 In the inner cavity of the extrusion die 18, a high pressure is applied to the castor oil liquid medium in the cavity of the extrusion cylinder 13 through the punch 6 connected to the press, so that the magnesium alloy blank 14 is subjected to the hydrostatic pressure of the surrounding high-pressure liquid. The hydrostatic pressure and appropriate temperature significantly improve the plasticity of the magnesium alloy blank 14 and decrease the deformation resistance. Under the action of the hydrostatic pressure generated by the high-pressure castor oil liquid, the magnesium alloy blank 14 is extruded into a wire or rod by a warm hydrostatic extrusion die, and passes through the extrusion nozzle 25, the conical cavity 23 in the cushion block 19, and the die base. The cylindrical cavity 24 in the cover plate 20 is extruded.

Embodiment 8: As shown in accompanying drawings 2 and 3, the extruding cylinder 13 described in this embodiment is composed of an outer cylinder 9, a middle cylinder 10 and an inner cylinder 11. The outer cylinder 9, the middle cylinder 10 and the The inner cylinder 11 is assembled together by cold pressing. The inclination angle β of the inner surface of the outer cylinder 9, the inner and outer surfaces of the middle cylinder 10 and the outer surface of the inner cylinder 11 is 1.5°. extrusion processing.

Specific embodiment nine: as shown in accompanying drawing 1, accompanying drawing 4 and accompanying drawing 5, the difference between this embodiment and specific embodiment 7 and 8 is that this embodiment also includes fluororubber O-ring 15 and beryllium copper wedge Ring 16, the fluororubber O-ring 15 and the beryllium copper wedge ring 16 are placed between the lower end of the movable punch 26 and the extrusion cylinder 13 and the beryllium copper wedge ring 16 is stacked on the fluororubber O-ring 15 The upper end of the upper end; the fluororubber O-ring 15 and the beryllium copper wedge ring 16 are also placed between the upper end of the die 18 and the extrusion cylinder 13 and the fluororubber O-ring 15 is stacked on the beryllium copper wedge ring 16 Adopting such a structure can realize sequential sealing in the temperature range of 0-380°C and the pressure range of 0-1500Mpa.

Embodiment 10: As shown in Figure 1, the difference between this embodiment and Embodiments 7, 8, and 9 is that this embodiment also includes an asbestos heat insulation board 27 and an aluminum silicate fiber heat insulation sleeve 12. The above-mentioned asbestos heat insulation board 27 is placed on the bottom surface of the extrusion cylinder 13, and the above-mentioned aluminum silicate fiber heat insulation sleeve 12 is sleeved on the outer surface of the extrusion cylinder 13. The disc-shaped asbestos heat insulation board 27 separates the extrusion cylinder 13 from the spacer 19, and the aluminum silicate fiber heat insulation sleeve 12 isolates the extrusion cylinder 13 from the air. This thermal insulation method can well ensure the heating speed of the magnesium alloy billet and the castor oil liquid extrusion medium.

Embodiment 11: As shown in accompanying drawing 5, the cone angle γ of the conical surface of the extrusion die opening 22 of the extrusion die 18 described in this embodiment is 22～62°, and the extrusion die opening 22 can It is compatible with the magnesium alloy blank whose cone angle α of the cone surface of the bar head is 20-60°.

Claims (10)

1. A method for manufacturing magnesium alloy wire or rod by thermostatic extrusion, characterized in that it is realized according to the following steps: 1. Magnesium alloy billet processing: select magnesium alloy rod stock, and process the magnesium alloy rod head A conical surface with a cone angle of 20-60°; 2. Lubricant application: mix castor oil and graphite in a weight ratio of 3-5:1 and apply it on the surface of the processed magnesium alloy blank; 3. Castor oil Heating: Preheat castor oil to 250-300°C; 4. Heating and temperature control of the warm-static liquid extrusion die: heat the warm-static liquid extrusion die to 250-300°C and control the temperature between 250-300°C 5. Put the magnesium alloy billet: put the magnesium alloy billet that completes step 2 into the extrusion die of a warm and static liquid extrusion die with a temperature of 250 to 300°C, the conical head of the magnesium alloy billet and the extrusion die mouth The conical surface cooperates, and the billet is directly heated through the hydrostatic extrusion die, so that the temperature of the magnesium alloy billet reaches 250-300°C; 6. Castor oil injection: inject castor oil with a temperature of 250-300°C into the hydrostatic extrusion die Seventh, put the movable punch: put the lower end of the movable punch into the upper part of the inner cavity of the extrusion cylinder; Eighth, pressurization: pressurize the movable punch, the magnesium alloy billet extrusion temperature Control at 250-300°C; 9. Extrusion forming: After the movable punch completes the extrusion stroke, the magnesium alloy wire or rod formed by warm and static liquid extrusion is extruded from the extrusion nozzle. 2. The thermostatic extrusion manufacturing method of magnesium alloy wire or rod according to claim 1, characterized in that in step 1, the head of the magnesium alloy rod is processed into a conical surface with a cone angle α of 38°. 3. The method for producing magnesium alloy wire or rod by thermostatic extrusion according to claim 1, characterized in that in step 2, castor oil and graphite are mixed in a weight ratio of 4:1 to prepare a lubricant. 4. The method for manufacturing magnesium alloy wire or rod by thermostatic extrusion according to claim 1, characterized in that the temperature of the thermostatic extrusion die in step 4 is controlled at 270°C. 5. The method for manufacturing magnesium alloy wire or rod by thermostatic extrusion according to claim 1, characterized in that the moving speed of the movable punch in step 8 is 5-15 mm/s. 6. Realize the magnesium alloy wire or rod thermostatic extrusion die in the magnesium alloy wire or rod thermostatic extrusion manufacturing method described in claim 1, which includes an upper template (1), a punch fixing sleeve (2), Punch pad (5), Punch (6), Extrusion cylinder (13), Die platen (17), Extrusion die (18), Pad (19), Die seat cover (20), mold base (21), armored thermocouple (31), temperature controller (29), electric heating tube (28), wire (30) and wire (34), and the upper template (1) is placed on the punch The upper end of the fixing sleeve (2) is connected with the punch fixing sleeve (2), the punch pad (5) is placed in the cylindrical hole (3) provided in the punch fixing sleeve (2), and the punch (6) The upper end of the upper end is placed in the conical hole (4) provided in the punch fixing sleeve (2), the cylindrical hole (3) and the conical hole (4) are connected, the mold seat cover plate (20), the spacer (19) , the extrusion cylinder (13), the die platen (17) are placed in order from bottom to top, and the extrusion die (18) is placed above the bottom pad (19) in the extrusion cylinder (13) , the die platen (17), the mold base cover plate (20) and the mold base (21) are fixedly connected, the electric heating tube (28) is installed in the electric heating tube hole (7) in the extrusion cylinder (13), and the electric heating tube ( 28) be electrically connected with temperature controller (29) by wire (34), temperature controller (29) is electrically connected with sheathed thermocouple (31) by wire (30), it is characterized in that it also comprises movable punch (26 ), the movable punch (26) is placed directly below the punch (6) and coaxial with the punch (6), and the lower end of the movable punch (26) passes through the middle of the die platen (17) and is provided with The punch through hole (8) is contained in the upper part in the extruding cylinder (13), and the extruding cylinder (13) is a multi-layer cold-press combined extruding cylinder. 7. The thermostatic liquid extrusion die for magnesium alloy wire or rod according to claim 6, characterized in that the extrusion cylinder (13) consists of an outer cylinder (9), a middle cylinder (10) and an inner cylinder (11) nesting composition, the inclination angle β of the inner surface of the outer cylinder (9), the inner and outer surfaces of the middle cylinder (10) and the outer surface of the inner cylinder (11) is 1.5 °. 8. The thermostatic liquid extrusion die for magnesium alloy wire or rod according to claim 6, characterized in that it also includes a fluorine rubber O-ring (15) and a beryllium copper wedge ring (16), the fluorine The rubber O-ring (15) and the beryllium copper wedge ring (16) are placed between the lower end of the movable punch (26) and the extrusion cylinder (13) and the beryllium copper wedge ring (16) is stacked on the fluororubber O The upper end of type ring (15); described fluorine rubber O type ring (15) and beryllium copper wedge ring (16) are also placed between the upper end periphery of extrusion die (18) and extrusion cylinder (13) And the fluorine rubber O type ring (15) is stacked on the upper end of the beryllium copper wedge ring (16). 9. The magnesium alloy wire or rod thermostatic extrusion die according to claim 6, characterized in that it also includes an asbestos heat insulation board (27) and an aluminum silicate fiber heat insulation sleeve (12), said The asbestos heat insulation board (27) is placed on the bottom surface of the extrusion cylinder (13), and the aluminum silicate fiber heat insulation sleeve (12) is sleeved on the outer surface of the extrusion cylinder (13). 10. The thermostatic liquid extrusion die for magnesium alloy wire or rod according to claim 6, characterized in that the cone angle of the conical surface of the extrusion die (22) of the extrusion die (18) is γ is 22-62°.

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