CN101850376A - Method and die for forward extrusion and variable diameter bending extrusion of magnesium alloy semi-solid billets - Google Patents

Method and die for forward extrusion and variable diameter bending extrusion of magnesium alloy semi-solid billets Download PDF

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CN101850376A
CN101850376A CN 201010194229 CN201010194229A CN101850376A CN 101850376 A CN101850376 A CN 101850376A CN 201010194229 CN201010194229 CN 201010194229 CN 201010194229 A CN201010194229 A CN 201010194229A CN 101850376 A CN101850376 A CN 101850376A
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die
extrusion
magnesium alloy
variable diameter
blank
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CN 201010194229
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CN101850376B (en
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田文彤
唐国兴
肖华星
杨辉
曹霞
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常州工学院
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Abstract

The invention discloses a method and a die for the forward extrusion and variable diameter bending extrusion of magnesium alloy semi-solid billets. The preparation method comprises a predeformation process and an isothermal spheroidizing heat treatment process, wherein in the predeformation process, uniform deformation of large deformation amount is realized by the die for the forward extrusion and variable diameter bending extrusion; cutting a magnesium alloy bar stock which is subjected to large deformation by a fixed size; heating the magnesium alloy bar stock cut by the fixed size at the temperature of between 520 and 580 DEG C under the protection of argon, and keeping the temperature of the obtained magnesium alloy bar stock for 10 to 30 minutes; and processing a bending extrusion angle of the die to be over 90 degrees. The method has the advantages of small predeformation resistance, large and uniform deformation, safety, reliability and no three-waste pollution. The grains of the prepared magnesium alloy semi-solid billets have fine size, are uniform and have a shape close to that of a sphere. The method solves the problem that the conventional SIMA method cannot continuously prepare the large-size semi-solid billets and meets the requirements of the semi-solid thixoforming workpieces for large-scale continuous production.

Description

Forward extrusion and the variable diameter bending pressing method and the mould of preparation magnesium alloy semi solid state base
Technical field
The invention belongs to the crimp field of magnesium alloy, particularly a kind of extrusion deforming processing method and processing mold that improves magnesium alloy mechanical property.
Background technology
Magnesium alloy is owing to have higher specific strength, specific stiffness, damping property, wearability, thermal conductivity, an electromagnetic wave shielding, free-cutting machinability and easy good comprehensive performances such as recovery property, and become the important new material of industries such as automobile, Aero-Space and telecommunications.In the energy, resource is increasingly serious and environmental issue is outstanding day by day today, magnesium alloy is described as " the green engineering structural material of 21 century ", and the lightweight magnesium alloy with good combination property is just becoming the focus that the whole world is paid close attention to.Along with the continuous increase of magnesium alloy structural part application percentage, also more and more higher to the requirement of Mg alloy formed technology.
The manufacturing process of magnesium alloy mainly is divided into liquid cast and plastic deformation two big classes.Because magnesium belongs to the close-packed hexagonal crystal structure, slip system is less, and temperature-room type plasticity is relatively poor, and present about 90% magnesium alloy engineering structure part all is by the casting method manufacturing.The casting of magnesium alloy making method has: sand casting, metal mold gravity casting, model casting, extrusion casint, low pressure casting and compression casting.These casting methods all need special-purpose magnesium alloy melting furnace, and need to adopt coverture or protective gas to prevent the oxidizing fire of magnesium in the fusion process, so fund input is big, and have serious environmental protection and security hidden trouble.Simultaneously, for the main forming method-compression casting method of magnesium alloy, though there are defectives such as shrinkage cavity, shrinkage porosite, pore in the complicated product that can be shaped, thereby have reduced the mechanical property of part when being shaped thick big and inhomogeneous foundry goods.And the magnesium alloy plastic working, though can improve part performance, can only the very simple product of production shape owing to the restriction that is subjected to its plastic deformation ability.
Semi-solid state forming technique has the advantage of casting and plastic working, can go out the high-quality magnesium alloy part of complicated shape with less power near-net-shape (only needing to process on a small quantity or do not reprocess, with regard to the plastic mechanical component that is used as).
The preparation of semisolid blank is the basic and crucial of semi-solid-state shaping.Its main preparation methods has at present: mechanical mixing method, electromagnetic stirring method, near liquidus casting, strain-induced fusing activation method (SIMA) etc.Because the easy oxidation characteristic of magnesium alloy, be equipped with magnesium alloy semi-solid state blank for liquid legal system and brought difficulty, and SIMA method technology is simple, the cost of equipment less investment, has avoided the drawback of melt easy oxidation when high temperature, so the SIMA method comes into one's own in the magnesium alloy semi-solid state blank preparation day by day.Existing SIMA method mainly is the extruding of jumping-up, equal channel angular, and wherein the jumping-up method not only is out of shape inhomogeneously, and the size of blank is very restricted; The magnesium alloy semi-solid state blank of isometrical road corner extruding preparation can only prepare the short blank of length owing to be subjected to the restriction of mould and equipment at every turn, and will be through the multi-pass extruding to obtain big equivalent strain.
Chinese patent literature CN100360700C (number of patent application 03132471.1) discloses a kind of magnesium alloy and has not waited curve extruding-shear-induced isothermal spheroidizing semisolid blank composite preparation process, blank is carried out not waiting the curve extruding, extrusion ratio remains between 1.5~2.0, bend extruding angle is 90 °, circulates repeatedly 3~4 times.But this method need can arrive reduced size with magnesium alloy grains through the multi-pass extruding, and operation is many, and production efficiency is low, the production cost height; And every time extrusion time is longer relatively, if improve extrusion speed the quality of product is descended.
Summary of the invention
The purpose of this invention is to provide a kind of forward extrusion and the variable diameter bending pressing method and mould that can prepare the magnesium alloy semi solid state base continuously.
The technical scheme that realizes the object of the invention is a kind of forward extrusion and variable diameter bending extrusion die for preparing the magnesium alloy semi solid state base, comprises cope match-plate pattern, punch, die, die case, cushion block, lower bolster and pressing plate; Die case is located and is fixed on the lower bolster, and the lower surface of die case contacts with the upper surface of lower bolster; Cushion block is placed in the bottom of die case central space; Die is provided with the charging aperture that is positioned at the upper end; Die is arranged on the top of cushion block, and is arranged in the die case central space; Punch is notch cuttype, and the charging aperture of the lower end aligned die of punch during use is fixedlyed connected in its upper end with cope match-plate pattern; The central authorities of pressing plate are provided with a through hole, and pressing plate is fixed on the upper surface of die case and die, and the charging aperture of its central through hole and die aligns; The die cavity of die comprises forward extrusion passage and variable diameter bending squeezing passage; The forward extrusion passage comprises first straight way and second straight way, and the charging aperture of first straight way also is the charging aperture of die; First straight way extends downwards vertically from the die top, links to each other with second straight way through the circular cone shape changeover portion, and wherein the sectional area of first straight way is greater than the sectional area of second straight way; The variable diameter bending squeezing passage is an extruding bend, and its bend extruding angle is 90 °~150 °, and the tail end of the sectional area of variable diameter bending squeezing passage from the head end on top to the bottom diminishes gradually; Isometrical exit passageway is set in the die case, and isometrical exit passageway is the passage of road outlet always, and the bearing of trend along the variable diameter bending squeezing passage in die case stretches out, and its sectional area is identical with the minimum sectional area of variable diameter bending squeezing passage.
The left part of above-mentioned die case and right part respectively have perforation through hole up and down, place the earthenware identical with the through hole height in the through hole, and heating wire is arranged in the earthenware.
A kind of forward extrusion and variable diameter bending pressing method for preparing the magnesium alloy semi solid state base, wherein employed extrusion die comprises cope match-plate pattern, punch, die, die case, cushion block, lower bolster and pressing plate; Die case is located and is fixed on the lower bolster, and the lower surface of die case contacts with the upper surface of lower bolster; Cushion block is placed in the bottom of die case central space; Die is provided with the charging aperture that is positioned at the upper end; Die is arranged on the top of cushion block, and is arranged in the die case central space; Punch is notch cuttype, and the charging aperture of the lower end aligned die of punch during use is fixedlyed connected in its upper end with cope match-plate pattern; The central authorities of pressing plate are provided with a through hole, and pressing plate is fixed on the upper surface of die case and die, and the charging aperture of its central through hole and die aligns; The die cavity of die comprises forward extrusion passage and variable diameter bending squeezing passage; The forward extrusion passage comprises first straight way and second straight way, and the charging aperture of first straight way also is the charging aperture of die; First straight way extends downwards vertically from the die top, links to each other with second straight way through the circular cone shape changeover portion, and wherein the sectional area of first straight way is greater than the sectional area of second straight way; The variable diameter bending squeezing passage is an extruding bend, and its bend extruding angle is 90 °~150 °, and the tail end of the sectional area of variable diameter bending squeezing passage from the head end on top to the bottom diminishes gradually; Isometrical exit passageway is set in the die case, and isometrical exit passageway is the passage of road outlet always, and the bearing of trend along the variable diameter bending squeezing passage in die case stretches out, and its sectional area is identical with the minimum sectional area of variable diameter bending squeezing passage; Described pressing method may further comprise the steps: the 1. machining of magnesium strand: the magnesium alloy cylindrical billet is processed into and the corresponding cylinder blank of the upper-end inner diameter of above-mentioned die; 2. the predeformation of blank: to through step 1. the blank of machining carry out preheating, make it to be warming up to 260 ℃~300 ℃; Above-mentioned extrusion die is fixed on the workbench of general extruder, extrusion die is carried out preheating, the temperature that makes extrusion die than blank preheat temperature low 40 ℃~60 ℃; The blank of preheating is put into the die of extrusion die, make the through hole in the middle of the pressing plate of punch by extrusion die of extrusion die blank is pressed into first straight way and sectional area compression less than second straight way of first straight way of the forward extrusion passage of die under the drive of hydraulic press, extrusion ratio is 15~30; It is descending that punch continues, and the blank after the forward extrusion is pressed into and carries out bend extruding and corner in the variable diameter bending squeezing passage greater than 90 ° detrusion; Next compact material is in the process that is pressed into forward extrusion passage and variable diameter bending squeezing passage, the preceding blank that once is trapped in the die is pressed into extrusion die die case isometrical exit passageway and extrude die, continue that extruding is then extruded die case with blank and the magnesium alloy bar that obtains predeformation; Said process carries out continuously; 3. will be through the 2. magnesium alloy bar scale cutting as required of predeformation of step; 4. isothermal heat treatment: make step 3. the magnesium alloy bar after the scale cutting in argon atmosphere, in resistance furnace, be heated to 520 ℃~580 ℃ of semi-solid temperature, insulation 10min~30min obtains the magnesium alloy semi solid state base, and wherein furnace temperature is heated to semi-solid temperature with first quick and back slow programming rate.
The 4. described semi-solid temperature that is warming up to blank first quick and back slow of above-mentioned steps, be earlier to make furnace temperature be raised to preceding 20 ℃~30 ℃ of the semi-solid temperature of magnesium alloy blank, then make furnace temperature slowly rise to semi-solid temperature with raise 1 ℃~2 ℃ speed of per minute with raise 13 ℃~15 ℃ speed of per minute.
2. in the predeformation process of blank, the extrusion speed of punch is 30 millimeters of per minutes to above-mentioned steps.
The present invention has positive effect: the made magnesium alloy semi-solid state blank crystallite dimension of (1) the present invention is tiny, evenly and approach spherical.(2) predeformation drag of the present invention is little, deflection is big and even, safe and reliable, three-waste free pollution.(3) partly realized very big plastic deformation in forward extrusion among the present invention, further strengthened distortion in extruding of subsequently bend and corner in the shearings greater than 90 degree, and the distortion in entire cross section is tending towards uniformity, solve the problem that traditional SIMA method can not prepare the large scale semisolid blank continuously, satisfied the needs of the large-scale continuous production of semi-solid die casting product.(4) the inventive method also can realize the suitability for industrialized production of low temperature extrusion modling, not only enhance productivity, and the magnesium alloy materials after the extruding has the mechanical property of crush resistance strength height, yield strength height, good extending performance.
Description of drawings
Fig. 1 is the mould schematic diagram of forward extrusion of the present invention and variable diameter bending extruding; Fig. 2 is that the A-A of Fig. 1 is to cutaway view; Fig. 3 is that the B of half die of Fig. 2 is to view; Fig. 4 is the heating-up temperature curve during AZ91D magnesium alloy blank isothermal processes among the embodiment 2; Fig. 5 is the limit micro-organization chart of portion of AZ91D magnesium alloy blank after the predeformation among the embodiment 2; Fig. 6 is the micro-organization chart of heart portion of AZ91D magnesium alloy blank after the predeformation among the embodiment 2; Fig. 7 pushes the grain refining effect figure of generation for AZ91D magnesium alloy blank among the embodiment 2 with the present invention; Fig. 8 pushes the grain refining effect figure of generation for AZ91D magnesium alloy blank among the embodiment 3 with the present invention; Fig. 9 pushes the grain refining effect figure of generation for AZ91D magnesium alloy blank among the embodiment 4 with the present invention; Figure 10 pushes the grain refining effect figure of generation for AZ91D magnesium alloy blank among the embodiment 5 with the present invention.
Mark in the above-mentioned accompanying drawing is as follows: cope match-plate pattern 1, punch 2, die 3, half dies 30, forward extrusion passage 31, the first straight way 31-1, the second straight way 31-2, variable diameter bending squeezing passage 32, die case 4, isometrical exit passageway 41, heating wire 42, earthenware 43, cushion block 5, lower bolster 6, pressing plate 7.
The specific embodiment
(forward extrusion and the variable diameter bending extrusion die of embodiment 1, preparation magnesium alloy semi solid state base) sees Fig. 1 to Fig. 3, and the forward extrusion and the variable diameter bending extrusion process mould of the preparation magnesium alloy semi solid state base of present embodiment comprise cope match-plate pattern 1, punch 2, die 3, die case 4, heating wire 42, earthenware 43, cushion block 5, lower bolster 6 and pressing plate 7.
Die case 4 is located and is fixed on the lower bolster 6, and the lower surface of die case 4 contacts with the upper surface of lower bolster 6; Cushion block 5 is placed in the bottom of die case 4 central space.Die 3 is provided with the charging aperture that is positioned at the upper end, and die 3 is arranged on the top of cushion block 5, is arranged in die case 4 central space, and die 3 and die case 4 matched in clearance; Punch 2 is notch cuttype, fixedlys connected with cope match-plate pattern 1 in its upper end, the charging aperture of the lower end aligned die 3 of punch 2 during use, and die 3 is chosen the monolateral 0.05mm that is with the clearance between punch and die of punch 2.The central authorities of pressing plate 7 are provided with a through hole, and pressing plate 7 is fixed on the upper surface of die case 4 and die 3, and the charging aperture of its central through hole and die 3 aligns.
The left part of above-mentioned die case 4 and right part respectively have perforation through hole up and down, place the earthenware 43 identical with the through hole height in the through hole, and heating wire 42 is arranged in the earthenware 43.
The whole die cavity of above-mentioned die 3 is made up of two half symmetrical fully dies 30, each half die 30 is equipped with squeezing passage half, it is shaped as semi-circular recesses, two and half dies 30 are fitted in opposite directions by a side that is provided with groove separately, constitute a complete die 3, form with bolting, two and half dies 30 are fixing with die case 4 by pressing plate 7 again.
The die cavity of die 3 comprises forward extrusion passage 31 and variable diameter bending squeezing passage 32, forward extrusion passage 31 above variable diameter bending squeezing passage 32 and two passages communicate.Forward extrusion passage 31 comprises the first straight way 31-1 and the second straight way 31-2, the charging aperture of the first straight way 31-1 also is the charging aperture of die 3, the first straight way 31-1 extends downwards vertically from die 3 tops, link to each other with the second straight way 31-2 through the circular cone shape changeover portion, wherein the sectional area of the first straight way 31-1 is greater than the sectional area of the second straight way 31-2; Variable diameter bending squeezing passage 32 is extruding bends, join until isometrical exit passageway 41 from extending to the oblique direction down of die 3 bottom of the second straight way 31-2 with die case 4, the sectional area of variable diameter bending squeezing passage 32 is from i.e. the diminishing gradually to the tail end that joins with die case 4 bottom of the second straight way 31-2 of the head end of topmost, and its bend extruding angle (also being the angle of bend of bend) is 120 °; The isometrical exit passageway 41 of above-mentioned die case 4 is the passages of road outlet always, and the bearing of trend along variable diameter bending squeezing passage 32 in die case 4 stretches out, and its sectional area is identical with the minimum sectional area of variable diameter bending squeezing passage 32.
(forward extrusion and the variable diameter bending pressing method of embodiment 2, preparation magnesium alloy semi solid state base) sees Fig. 4 to Fig. 7, present embodiment prepares the forward extrusion and the used extrusion die of angle, reducing road pressing method of magnesium alloy semi solid state base, adopt embodiment 1 resulting mould, present embodiment is handled to be AZ91D magnesium alloy strand, the method for preparing the magnesium alloy semi solid state base may further comprise the steps: the 1. machining of magnesium strand: the magnesium alloy cylindrical billet is processed into and the corresponding cylinder blank of the upper-end inner diameter of die 3, the diameter of blank is 50mm, highly is 120mm.
2. the predeformation of blank: will be through 1. cylinder blank preheating in chamber type electric resistance furnace of machining of step, preheat temperature is 280 ℃, insulation 20min.The extrusion die of embodiment 1 is fixed on the workbench of general extruder, and makes punch 2 to slide relatively up and down with respect to die 3.The heating wire 42 that will be arranged on again in the mould is connected power supply, and extrusion die is carried out preheating, makes mold temperature reach 220 ℃.The cylinder blank of preheating is put into the die 3 of extrusion die, under the drive of hydraulic press, make the punch 2 of extrusion die blank is pressed among the first straight way 31-1 and the second straight way 31-2 of sectional area of forward extrusion passage 31 less than the first straight way 31-1 by the through hole in the middle of the pressing plate 7 of extrusion die, extrusion speed is 30 millimeters of per minutes, thereby produce big compression, extrusion ratio (pushing the total area of section of preceding goods and the ratio of total area of section of extruding back goods) is 15~30 (present embodiment is 17); Punch 2 continues descending, be pressed in the variable diameter bending squeezing passage 32 through the blank after the forward extrusion (direction of motion is identical with the direction of suffered extruding force), in reducing distortion and 120 degree bend extrusion shearing distortion (flexural deformation that is taken place when in one section passage, advancing), further add large deformation; When punch 2 come downwards to the first straight way 31-1 the lower end and can't be descending again the time, punch 2 is up, next cylinder blank is put into die 3, next piece cylinder blank of punch 2 descending extruding then, next piece cylinder blank is in the process that is pressed into forward extrusion passage 31 and variable diameter bending squeezing passage 32, the preceding blank that once is trapped in the die 3 is pressed into extrusion die die case 4 isometrical exit passageway 41 and extrude die 3, continue that extruding is then extruded die case 4 with blank and the magnesium alloy bar that obtains predeformation; Said process carries out continuously, heating wire 42 is switched on always, make that the temperature of blank keeps 280 ℃ in the predeformation process, the equivalent strain during predeformation (under one strain regime each components of strain through appropriate combination and that form and strain unidirectional strain equivalence) is 5.1.
3. will be through the 2. magnesium alloy bar scale cutting (carrying out the cutting of certain-length in the axial direction) as required of predeformation of step.
4. isothermal heat treatment: make step 3. the magnesium alloy bar after the scale cutting in argon atmosphere, in resistance furnace, be heated to 565 ℃ of semi-solid temperature in first quick and back slow mode, be incubated 20min then and obtain the magnesium alloy semi solid state base; Concrete temperature-rising method is: furnace temperature changes Control of Voltage by pressure regulator during heating, speed with 13.5 ℃ of per minute risings makes furnace temperature be raised to preceding 20 ℃~30 ℃ of the semi-solid temperature (present embodiment is 30 ℃) of magnesium alloy blank, then the speed with 1 ℃ of per minute rising makes furnace temperature slowly rise to semi-solid temperature, also is isothermal temperature.
See Fig. 5 and Fig. 6, the purpose of the predeformation of above-mentioned steps in 2. is to obtain enough strains of bringing out, and this step is to obtain the basis of even tiny subsphaeroidal semisolid blank and crucial; In predeformation technology, will push, reducing extruding is compound dexterously with the detrusion extrusion technique, realized forward extrusion distortion, corner simultaneously greater than 90 ° reducing detrusion in once extruding, its equivalent strain can reach more than 5.(SIMA strain-induced fusing activation method technological principle: utilize traditional casting method to obtain foundry goods, this metal stock is carried out hot extrusion deformation in the temperature range of recovery and recrystallization, broken as cast condition arborescent structure, storage compartment changes energy in the tissue of blank, can on demand the metal stock through distortion be cut into certain size at last, be heated solid-liquid two-phase region and suitably insulation rapidly,, can obtain to have thixotropic spherical semi solid slurry by the release of deformation energy.Therefore, above said enough strains of bringing out, can be understood as the enough variation energy of storage in the blank tissue).
See Fig. 4, the above-mentioned steps 4. heat treated purpose of isothermal is to obtain needed solid-liquid phase ratio and make the primary phase spheroidization.Firing rate when semi-solid isothermal is handled is taked principle first quick and back slow, though be because fast firing rate can be enhanced productivity effectively, but can cause that the non-uniform temperature in the blank distributes, and liquid does not have time enough to soak into the grain boundary, cause the liquid outflow, make the mobile variation of semi-solid blank; And when firing rate is slow, not only influence production efficiency, and the easy alligatoring of crystal grain grows up, and when heating-up temperature was higher, blank was difficult to keep the shape of himself.Therefore, the selection principle of firing rate should be when guaranteeing evenly heating, is heated to the temperature of setting with the fastest speed, can avoid blank at high temperature to keep the long period again and the unfavorable factors such as grain growth that cause, thereby take principle first quick and back slow.
The present invention combines the advantage of large extrusion ratio crimp and variable diameter bending crimp, the magnesium alloy blank is in the mobile extrusion process used for forming of the variable diameter bending squeezing passage of die, the metal inside tissue presents certain directionality, crystal grain is elongated even fragmentation takes place, increased again crystallization nucleation rate (the nucleus number that in unit interval, unit volume, forms in the parent phase), refinement crystal grain.
(forward extrusion and the variable diameter bending pressing method of embodiment 3, preparation magnesium alloy semi solid state base) sees Fig. 8, the difference of present embodiment and embodiment 2 is: step 2. in, through 1. blank preheating in chamber type electric resistance furnace of machining of step, preheat temperature is 300 ℃, insulation 15min, mold temperature was 240 ℃ when extrusion die was carried out preheating, and the predeformation temperature of blank is that the temperature of blank in the predeformation process is 300 ℃.
Present embodiment has improved the predeformation temperature than embodiment 2, can make average crystal grain diameter become big, but present embodiment has reduced the predeformation temperature retention time, and average crystal grain diameter is diminished; Compare embodiment 1, the rising of present embodiment predeformation temperature all can make the grain shape coefficient (ratio of the external surface area of the ball that the external surface area of solid particle is identical with volume and solid particle with the minimizing of predeformation temperature retention time; Because in the identical and variform object of volume, with the external surface area minimum of ball, so the form factor perseverance is greater than 1; The size of form factor illustrates that particle bumps against and the difference degree of ball, if it is worth more near 1, then its shape also just approaches ball more) become greatly, that is the shape of crystal grain is more irregular.
(forward extrusion and the variable diameter bending pressing method of embodiment 4, preparation magnesium alloy semi solid state base) sees Fig. 9, the difference of present embodiment and embodiment 3 is: step is 2. in the predeformation process, through 1. blank preheating in chamber type electric resistance furnace of machining of step, preheat temperature is 300 ℃, insulation 10min.
Step is 4. in the isothermal heat treatment process of blank, with step 4. the blank after the scale cutting in argon atmosphere, in resistance furnace, be heated to 580 ℃, insulation 20min; Concrete grammar is: furnace temperature changes Control of Voltage by pressure regulator during heating, furnace temperature is raised to 580 ℃ method: make furnace temperature be raised to 560 ℃ with raise 13.5 ℃ speed of per minute earlier, then the speed with 1 ℃ of per minute rising makes furnace temperature slowly rise to semi-solid temperature, also is isothermal temperature.
Compare embodiment 3, the form factor of present embodiment crystal grain is near 1; Though have certain change big because present embodiment predeformation temperature retention time causes form factor than short-range missile, but the heat treated temperature of isothermal is higher, in identical isothermal temperature retention time, the heating-up temperature of blank is high more, and the form factor of crystal grain is more little and reduced form factor greatly.
(forward extrusion and the variable diameter bending pressing method of embodiment 5, preparation magnesium alloy semi solid state base) sees Figure 10, the difference of present embodiment and embodiment 4 is: step is 4. in the isothermal heat treatment process of blank, 3. the blank after scale cuts with step is heated to 580 ℃ in resistance furnace in argon atmosphere, insulation 30min.
Compare with embodiment 4, the form factor of present embodiment crystal grain is more near 1; Because identical isothermal temperature, isothermal time are long more, the form factor of crystal grain is more little.

Claims (5)

1. a forward extrusion and a variable diameter bending extrusion die for preparing the magnesium alloy semi solid state base comprises cope match-plate pattern (1), punch (2), die (3), die case (4), cushion block (5), lower bolster (6) and pressing plate (7); Die case (4) is located and is fixed on the lower bolster (6), and the lower surface of die case (4) contacts with the upper surface of lower bolster (6); Cushion block (5) is placed in the bottom of die case (4) central space; Die (3) is provided with the charging aperture that is positioned at the upper end; Die (3) is arranged on the top of cushion block (5), and is arranged in die case (4) central space; Punch (2) is notch cuttype, and the charging aperture of the lower end aligned die (3) of punch during use (2) is fixedlyed connected in its upper end with cope match-plate pattern (1); The central authorities of pressing plate (7) are provided with a through hole, and pressing plate (7) is fixed on the upper surface of die case (4) and die (3), and the charging aperture of its central through hole and die (3) aligns; It is characterized in that: the die cavity of die (3) comprises forward extrusion passage (31) and variable diameter bending squeezing passage (32); Forward extrusion passage (31) comprises first straight way (31-1) and second straight way (31-2), and the charging aperture of first straight way (31-1) also is the charging aperture of die (3); First straight way (31-1) extends downwards vertically from die (3) top, links to each other with second straight way (31-2) through the circular cone shape changeover portion, and wherein the sectional area of first straight way (31-1) is greater than the sectional area of second straight way (31-2); Variable diameter bending squeezing passage (32) is an extruding bend, and its bend extruding angle is 90 °~150 °, and the tail end of the sectional area of variable diameter bending squeezing passage (32) from the head end on top to the bottom diminishes gradually; Isometrical exit passageway (41) is set in the die case (4), isometrical exit passageway (41) is the passage of road outlet always, bearing of trend along variable diameter bending squeezing passage (32) in die case (4) stretches out, and its sectional area is identical with the minimum sectional area of variable diameter bending squeezing passage (32).
2. the forward extrusion of preparation magnesium alloy semi solid state base according to claim 1 and variable diameter bending extrusion die, it is characterized in that: the left part of die case (4) and right part respectively have perforation through hole up and down, place the earthenware (43) identical with the through hole height in the through hole, heating wire (42) is arranged in the earthenware (43).
3. a forward extrusion and variable diameter bending pressing method for preparing the magnesium alloy semi solid state base, it is characterized in that: wherein employed extrusion die comprises cope match-plate pattern (1), punch (2), die (3), die case (4), cushion block (5), lower bolster (6) and pressing plate (7); Die case (4) is located and is fixed on the lower bolster (6), and the lower surface of die case (4) contacts with the upper surface of lower bolster (6); Cushion block (5) is placed in the bottom of die case (4) central space; Die (3) is provided with the charging aperture that is positioned at the upper end; Die (3) is arranged on the top of cushion block (5), and is arranged in die case (4) central space; Punch (2) is notch cuttype, and the charging aperture of the lower end aligned die (3) of punch during use (2) is fixedlyed connected in its upper end with cope match-plate pattern (1); The central authorities of pressing plate (7) are provided with a through hole, and pressing plate (7) is fixed on the upper surface of die case (4) and die (3), and the charging aperture of its central through hole and die (3) aligns; The die cavity of die (3) comprises forward extrusion passage (31) and variable diameter bending squeezing passage (32); Forward extrusion passage (31) comprises first straight way (31-1) and second straight way (31-2), and the charging aperture of first straight way (31-1) also is the charging aperture of die (3); First straight way (31-1) extends downwards vertically from die (3) top, links to each other with second straight way (31-2) through the circular cone shape changeover portion, and wherein the sectional area of first straight way (31-1) is greater than the sectional area of second straight way (31-2); Variable diameter bending squeezing passage (32) is an extruding bend, and its bend extruding angle is 90 °~150 °, and the tail end of the sectional area of variable diameter bending squeezing passage (32) from the head end on top to the bottom diminishes gradually; Isometrical exit passageway (41) is set in the die case (4), isometrical exit passageway (41) is the passage of road outlet always, bearing of trend along variable diameter bending squeezing passage (32) in die case (4) stretches out, and its sectional area is identical with the minimum sectional area of variable diameter bending squeezing passage (32); Described pressing method may further comprise the steps:
1. the machining of magnesium strand: the magnesium alloy cylindrical billet is processed into the corresponding cylinder blank of upper-end inner diameter with above-mentioned die (3);
2. the predeformation of blank: to through step 1. the blank of machining carry out preheating, make it to be warming up to 260 ℃~300 ℃; Above-mentioned extrusion die is fixed on the workbench of general extruder, extrusion die is carried out preheating, the temperature that makes extrusion die than blank preheat temperature low 40 ℃~60 ℃; The blank of preheating is put into the die (3) of extrusion die, make the through hole in the middle of the pressing plate (7) of punch (2) by extrusion die of extrusion die blank is pressed into first straight way (31-1) and sectional area compression less than second straight way (31-2) of first straight way (31-1) of the forward extrusion passage (31) of die (3) under the drive of hydraulic press, extrusion ratio is 15~30; It is descending that punch (2) continues, and the blank after the forward extrusion is pressed into and carries out bend extruding and corner in the variable diameter bending squeezing passage (32) greater than 90 ° detrusion; Next compact material is in the process that is pressed into forward extrusion passage (31) and variable diameter bending squeezing passage (32), the preceding blank that once is trapped in the die (3) is pressed into extrusion die die case (4) isometrical exit passageway (41) and extrude die (3), continue that extruding is then extruded blank die case (4) and the magnesium alloy bar that obtains predeformation; Said process carries out continuously;
3. will be through the 2. magnesium alloy bar scale cutting as required of predeformation of step;
4. isothermal heat treatment: make step 3. the magnesium alloy bar after the scale cutting in argon atmosphere, in resistance furnace, be heated to 520 ℃~580 ℃ of semi-solid temperature, insulation 10min~30min obtains the magnesium alloy semi solid state base, and wherein furnace temperature is heated to semi-solid temperature with first quick and back slow programming rate.
4. the forward extrusion of preparation magnesium alloy semi solid state base according to claim 3 and variable diameter bending pressing method, it is characterized in that: the 4. described semi-solid temperature that is warming up to blank first quick and back slow of step, be earlier to make furnace temperature be raised to preceding 20 ℃~30 ℃ of the semi-solid temperature of magnesium alloy blank, then make furnace temperature slowly rise to semi-solid temperature with raise 1 ℃~2 ℃ speed of per minute with raise 13 ℃~15 ℃ speed of per minute.
5. the forward extrusion of preparation magnesium alloy semi solid state base according to claim 3 and variable diameter bending pressing method is characterized in that: 2. in the predeformation process of blank, the extrusion speed of punch (2) is 30 millimeters of per minutes to step.
CN2010101942295A 2010-06-08 2010-06-08 Method and die for forward extrusion and variable diameter bending extrusion of magnesium alloy semi-solid billets CN101850376B (en)

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CN102240693A (en) * 2011-05-10 2011-11-16 太原科技大学 Mould for refining magnesium alloy structure and enhancing mechanical property
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CN102240693B (en) * 2011-05-10 2013-08-28 太原科技大学 Mould for refining magnesium alloy structure and enhancing mechanical property
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CN103042034A (en) * 2012-12-29 2013-04-17 重庆理工大学 Method and die for preparing magnesium alloy board with multistage continuous corner cutting deformation
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CN103170602B (en) * 2013-03-14 2015-07-22 哈尔滨工业大学 Preparation method of Titanium-Copper (Ti-Cu) type titanium alloy semi-solid blank
CN103331319A (en) * 2013-07-16 2013-10-02 东北大学 Stepping continuous extrusion device and method for metal severe plastic deformation
CN103464727A (en) * 2013-09-18 2013-12-25 太原理工大学 Method for preparing reinforced magnesium alloy block-coated magnesium alloy bar
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CN105223075B (en) * 2014-07-04 2018-02-23 北京有色金属研究总院 A kind of metal semi-solid thixotroping shaping simulation test device and method
CN106493372A (en) * 2016-11-24 2017-03-15 上海电机学院 The ball milling bending channel extruding curing of the discarded chip circular treatment of pure titanium
CN106513690A (en) * 2016-11-24 2017-03-22 上海电机学院 Ball milling-isometric angle extrusion-annealing method for pure titanium waste chip circular curing
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