CN106607468A - Differential-speed extrusion forming method of magnesium alloy high performance cup-shaped piece - Google Patents

Differential-speed extrusion forming method of magnesium alloy high performance cup-shaped piece Download PDF

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Publication number
CN106607468A
CN106607468A CN201710024674.9A CN201710024674A CN106607468A CN 106607468 A CN106607468 A CN 106607468A CN 201710024674 A CN201710024674 A CN 201710024674A CN 106607468 A CN106607468 A CN 106607468A
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China
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die
cavity
shaped
extrusion
magnesium alloy
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CN106607468B (en
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薛勇
陈帅帅
张治民
李国俊
王强
白冰
杨博文
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North University of China
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North University of China
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21CMANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C23/00Extruding metal; Impact extrusion
    • B21C23/02Making uncoated products
    • B21C23/18Making uncoated products by impact extrusion
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21CMANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C23/00Extruding metal; Impact extrusion
    • B21C23/32Lubrication of metal being extruded or of dies, or the like, e.g. physical state of lubricant, location where lubricant is applied
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21CMANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C25/00Profiling tools for metal extruding
    • B21C25/02Dies

Abstract

The invention provides a differential-speed extrusion forming method of a magnesium alloy high performance cup-shaped piece and relates to the technical field of metal and plastic machining and forming. A combined concave die is adopted and comprises a T-shaped upper concave die body and a U-shaped lower concave die body. The T-shaped upper concave die body is internally provided with a cylindrical cavity and installed on the U-shaped lower concave die body, and the section of a formed revolved cavity is shaped like a Chinese character 'shan'. Staggered 'ladder' type differential-speed extrusion steps are adopted for the bottom of the extrusion cavity shaped like the Chinese character 'shan'. Three stages of deformation are conducted, the first stage is the axial similar cylinder pier coarse deformation stage, the second stage is the radial extrusion large deformation stage, and the third stage is the corner extrusion and shearing deformation stage. The extrusion cavity shaped like the Chinese character 'shan' and the staggered 'ladder' type differential-speed extrusion steps at the cavity bottom are adopted for extruding the magnesium alloy high performance cup-shaped piece, the magnesium alloy material forming capacity is greatly improved, a high-density structure is obtained, great plastic deformation is obtained, the grain refining effect is remarkable, the effect of eliminating grain dual-mode distribution of the barrel wall of the cup-shaped piece is obvious, and the fabrication procedure of the high performance magnesium alloy cup-shaped piece is shortened.

Description

A kind of differential-velocity extrusion manufacturing process of magnesium alloy high-performance cup shell
Technical field
The present invention relates to Metal Forming technique and forming technique field, and in particular to a kind of to squeeze for magnesium alloy materials Pressing formation and modified differential-velocity extrusion manufacturing process.
Background technology
Cup-shape member is one of most representational version in the fields such as Aero-Space, defence and military, transportation, is The typical product of reversal extrusion technique.For cup shell manufacture, mostly using backward extrusion technology, reversal extrusion technique is one Advanced machining process with less cutting is planted, the form and dimensional precision of forging is not only increased, has been saved metal material, and because of gold Category fibre flow improves the mechanical performance of such part in profiling, the characteristics of with " efficiently, high-quality, low energy consumption ", Technology and economically there is very high use value, it has also become fall over each other the focus studied both at home and abroad.
Magnesium alloy cup shell needs multi-pass jumping-up pulling base to reach preferably using the method for traditional backward extrusion Substantially, the tensile strength difference of its circumferential and axial is larger for refined crystalline strengthening effect, low production efficiency and formed parts anisotropy. Therefore, research and develop the new manufacturing process of magnesium alloy with high strength and ductility cups and there is conscientiously important meaning.
Published China Patent No. is ZL201410820158.3 patent names for " annular of magnesium alloy cup-shape member is led to Road corner extrusion shaping dies and method " is a kind of new manufacturing process for preparing cup-shaped member, belongs to large plastometric set category, There is very big technical advantage compared to traditional backward extrusion method, the average equivalent plastic strain of drip molding is up to tradition backward extrusion More than 2 times, its plastic force is little, and deflection is big, and the equivalent plastic strain distribution of drip molding is more uniform, brilliant for cup-shape member Grain refinement and the lifting of mechanical property tool have certain effect and effect.
But study find, by patent " the circular passage corner extrusion shaping dies of magnesium alloy cup-shape member and method " into The cup shell of shape, on the face perpendicular to metal flow direction, crystal grain is in representative dual-mode state crystal grain distribution to barrel.Bimodal crystal grain Distribution refers to that metal is crushed elongations in the presence of extrusion chamber inner conical boss, and the original coarse grain in part is obtained significantly carefully Change, the thick crystal grain in part is distributed in strip.Afterwards crystal grain distribution form is very much like with Equal-channel Angular Pressing (ECAP) for this. The ductile rupture that the bi-modal distribution phenomenon of crystal grain causes cup shell barrel sample axial tension fracture mechanism to be fine grain band is adjoint The mixed fracture mechanism that the Brittle cleavage fracture of coarse region combines, reduces to a certain extent the plasticity and mechanical property of cups Energy.Obviously, barrel crystal grain bi-modal distribution governs high tough cup shell research and development and production practices.With regard to this apparently, " magnesium is closed patent There is certain technical limitation in the circular passage corner extrusion shaping dies of golden cup-shape member and method ".
The content of the invention
It is an object of the invention to provide a kind of differential-velocity extrusion manufacturing process of magnesium alloy high-performance cup shell, the method can be come Bigger average equivalent strain is obtained, grain refining effect is improved, significantly reduces the cup-shaped of circular passage corner extrusion shaping The barrel of part is in bimodal crystal grain distribution, reduces the incidence rate that barrel mixes tension failure mechanism.
In order to solve the problems of background technology, the present invention is to employ the following technical solutions:
A kind of differential-velocity extrusion manufacturing process of magnesium alloy high-performance cup shell, it sequentially includes:
(1) bar material baiting;
(2) homogenization heat treatment, forms magnesium alloy blank;
(3) prepare before shaping:Magnesium alloy blank is heated to into forming temperature and is incubated, and differential-velocity extrusion shaping dies are whole Body is preheated to more than magnesium alloy blank forming temperature and is incubated;Described differential-velocity extrusion shaping dies include the top with forcing press The mold component of structure connection and the lower die assembly and combined die of the connection of forcing press substructure;Described is upper Die assembly includes that the upper bolster that the upper die plate being connected with the upper table of forcing press connects with upper die plate covers and upper bolster set Built-in drift;Described upper die plate fastening bolt is assemblied on forcing press upper table, and the upper ends of the drift exist On the inside center line of upper bolster set, drift upper end by cylinder finger setting, surrounding by hexagon socket head cap screw upper bolster set with it is upper Template is fixed, and drift is firmly anchored in upper bolster set;Described combined die includes, under "T"-shaped upper cavity die and " u "-shaped Die, described "T"-shaped upper cavity die inside is cylindrical mold cavity, is coordinated with drift gap, and "T"-shaped upper cavity die upper end is provided with annular The spacing cooperation of end cone face on the conical surface, with die shoe set die cavity;Described " u "-shaped lower cavity die inside is revolving body die cavity;On "T"-shaped Die is arranged in the revolving body die cavity of " u "-shaped lower cavity die, the cross sectional shape that revolving body die cavity and cylindrical mold cavity are collectively constituted For " mountain " font extrusion chamber;Described lower die assembly includes lower template cover for seat, lower bolster and lower template;Described die shoe set Internal is cylindrical mold cavity, and die cavity inside coordinates with combined die gap, and die cavity upper end is closed up with circular cone, with to fovea superior The spacing load of mould;Die shoe covers and lower bolster is fixed on from top to bottom in lower template.
(4), installation mold:By the mould installion after preheating insulation on forcing press;Give combined die inner chamber injection oil Agent graphitic lubricant, while from fovea superior die tip aperture from top to bottom toward " mountain " font extruding intracavity injection oil preparation graphite lubrication Agent;The upper cavity die cylindrical type intracavity of combined die will be put into through the magnesium alloy blank of homogenization heat treatment;
(5) forming process:Forcing press drives the upper die plate of mold component, upper bolster set and drift to move downward, and extrudes Magnesium alloy blank extrudes intracavity along die cavity flow deformation in " mountain " font;Effect of the magnesium alloy blank in cylindrical punch pressure Under, through the deformation of three phases:One is through the axially upset deformation stage of similar cylinder;Two is radial compression large deformation rank Section;As forcing press drives drift to continue to be pressed down against, metal starts along " mountain " font extrusion chamber bottom radial compression, this process In, metal flows through undergauge after differential-velocity extrusion band and is squeezed into the less squeezing passage of internal diameter;Three is corner extrusion detrusion rank Section;Forcing press drives drift to continue to be pressed down against metal into " mountain " font extrusion chamber bottom roundings region, and metal should by shearing Power effect is flowed axially upwards along die wall, forms the barrel of magnesium alloy cup shell;
(6) after the completion of extrusion molding:Stop moving downward for forcing press upper table;Tighten upper die plate to connect with die shoe set The fastening bolt for connecing, unclamps the fastening bolt of die shoe set, lower bolster and lower template junction;Forcing press upper table reversely to Upper motion, drives drift to rise and departs from cup shell, while upper die plate drives die shoe set to rise, it is de- with combined die From;Push rod is acted on by hydraulic cylinder liftout tank, magnesium alloy cup shell is ejected from combined die.
The present invention principle be:Devise combined die structure, "T"-shaped fovea superior mold cavity and the recessed mold cavity of " u "-shaped It is collectively forming " mountain " shaped rotary build chamber, particularly cavity bottom and employs " ladder " formula differential-velocity extrusion step.The length of step Spend for a, a height of h, neighbouring step transition band level inclination is α, and transitional radius are r.So-called differential, refers to "T"-shaped " ladder " step of " ladder " step of upper cavity die lower surface and the recessed mold cavity of the " u "-shaped of corresponding lower position is in longitudinal direction Have that dislocation is poor, when metal flows through this region in extrusion process, metal upper and lower surface forms difference along step-flow, flow velocity Speed.In view of law of metal flow, the present invention adopts the upper and lower longitudinally displaced distance of " ladder " step for half length of bench a/2 (through Deform-3D finite element modellings, average equivalent plastic strain is maximum when dislocation distance is a/2).
Change magnesium alloy blank by controlling technological parameter (step number, step length to height ratio a/h, intermediate zone inclination alpha) Stressing conditions in extrusion process used for forming, so as to control metal stresses state, equivalent strain amount, degree of grain refinement, plasticity Deformation and structural homogenity etc..Metal is flowed through after " ladder " formula differential-velocity extrusion step, metal upper and lower surface be squeezed step shearing The effect of stress;Simultaneously because up and down " ladder " formula radial compression step has a dislocation poor, cause metal in this Regional contraction Upper and lower surface extrusion speed is inconsistent, and metal inside can also produce moment of torsion and shear stress;In addition, " staged " radial compression step The crush-zone for being constituted is that inlet calibre is big, and outlet bore is little, and metal is also subject to " staged " when this region is squeezed into Radial compression step axial direction extruding force.
These three factors change the stress state of metal jointly, cause metal surface and inside to obtain bigger plasticity Deflection, increased average equivalent strain, obtain higher compact texture, and tissue thinning effect is notable, " staged " radial compression Step effectively increases deforming degree of the metal in extrusion process, has significantly crushed traditional backward extrusion technology cup shell microcosmic The distribution of flat elongate strip is organized as, CRYSTALLITE SIZES is more uniformly spread, it is bright to eliminating crystal grain bi-modal distribution phenomenon effect It is aobvious.
Description of the drawings
In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing The accompanying drawing to be used needed for having technology description is briefly described, it should be apparent that, drawings in the following description are only this Some embodiments of invention, for those of ordinary skill in the art, on the premise of not paying creative work, can be with Other accompanying drawings are obtained according to these accompanying drawings.
Fig. 1 is blank mold work view in extrusion molding in embodiment provided by the present invention;
Fig. 2 is blank mold work view when to be extruded in embodiment provided by the present invention;
Fig. 3-1 is combined die assembling schematic diagram in embodiment provided by the present invention;
Fig. 3-2 is combined die cavity lower end close-up schematic view in embodiment provided by the present invention;
Fig. 4-1 is " ladder " formula differential radial compression step schematic diagram in embodiment provided by the present invention;
Fig. 4-2 is " ladder " formula differential radial compression step schematic diagram misplaced in embodiment provided by the present invention;
Fig. 5 is the crimp metal flow subregion schematic diagram of extrusion in embodiment provided by the present invention;
Fig. 6 is the magnesium alloy cup-shape member schematic diagram of extrusion molding in embodiment provided by the present invention;
Fig. 7 is the cup shell barrel position metallographic microstructure of prior art annular passage corner extrusion shaping;
Fig. 8 is the cup shell barrel position metallographic microstructure of embodiment differential-velocity extrusion shaping provided by the present invention;
Reference:
1- upper die plates;2- upper bolster sets;3- die shoe sets;The "T"-shaped upper cavity dies of 4-;5- " u "-shaped lower cavity dies;6- lower bolsters; 7- lower templates;8- straight pins;9- push rods;10- screws;11- jacking blocks;12- drifts;13- compression springs;14- fastening bolts;15- Vertical direction hole;16- " mountain " font extrusion chamber;17- differential-velocity extrusion steps;18- annular boss.
Specific embodiment
In order that the objects, technical solutions and advantages of the present invention become more apparent, below in conjunction with accompanying drawing and it is embodied as Mode, the present invention will be described in further detail.It should be appreciated that specific embodiment described herein is only to explain this Invention, is not intended to limit the present invention.
Fig. 1-Fig. 6 is referred to, this specific embodiment is employed the following technical solutions:A kind of magnesium alloy high-performance cup shell Differential-velocity extrusion shaping dies, the mold component being connected including the superstructure with forcing press and forcing press substructure connect Lower die assembly and combined die.
Fig. 1-Fig. 2 is referred to, described mold component includes:The upper die plate 1 that is connected with the superstructure of press and on The upper bolster set 2 and upper bolster that template 1 connects covers built-in drift 12.The upper ends of the drift 12 cover 2 in upper bolster Inside center.
Refer to Fig. 3-1, described combined die, including "T"-shaped upper cavity die 4 and " u "-shaped lower cavity die 5.Described " T " The inside of shape upper cavity die 4 is cylindrical mold cavity, is coordinated with the gap of drift 12, and the upper end of "T"-shaped upper cavity die 4 is provided with circular cone, with Die holder covers the spacing cooperation of end cone face on 3 die cavities.The described inside of " u "-shaped lower cavity die 5 is revolving body die cavity."T"-shaped upper cavity die 4 is pacified It is mounted in the revolving body die cavity of " u "-shaped lower cavity die 5, the cross sectional shape that cylindrical mold cavity and revolving body die cavity are collectively constituted is " mountain " Font extrusion chamber 16;The upper end of "T"-shaped upper cavity die 4 in axial direction arranges equidistant vertical direction hole 15, is through to " mountain " word Shape extrusion chamber 16, as lubricant flow channel.
Fig. 3-2 are referred to, the lower end surface section of "T"-shaped upper cavity die 4 is " ladder " formula differential-velocity extrusion step 17, right therewith The lower section lengthwise position answered, in the mold cavity surface of " u "-shaped lower cavity die 5 " ladder " formula differential-velocity extrusion step 17 is also provided with.It is "T"-shaped The outside lower end of upper cavity die 4 is provided with an annular boss, is the extruding calibrating strap of cup shell internal diameter.Corresponding lateral attitude, One section of annular boss is equally provided with the die cavity of " u "-shaped lower cavity die 5, is the extruding calibrating strap of cup shell external diameter, the extruding is determined Footpath band and the tangent connection of " u "-shaped lower cavity die cavity bottom fillet.
Refer to Fig. 1, Fig. 2, described lower die assembly includes die shoe set 3, lower bolster 6 and lower template 7, it is described under It is cylindrical mold cavity inside die holder set 3, die cavity inside coordinates with combined die gap, and die cavity upper end is closed up with circular cone, With to the spacing load of "T"-shaped upper cavity die 4;Die shoe set 3 and lower bolster 6 are fixed on from top to bottom in lower template 7;It is knockdown "T"-shaped upper cavity die 4, " u "-shaped lower cavity die 5 are positioned with lower bolster 6 by straight pin 8, and with screw 10 lower mould is fixed on from top to bottom On plate 7.
Described lower bolster 6 and the middle part of lower template 7 is equipped with and knockdown "T"-shaped upper cavity die 4, the bottom of " u "-shaped lower cavity die 5 The push-rod hole that through hole is communicated, described jacking block 11 is placed in the inner chamber of combination type " u "-shaped lower cavity die 5, with interior cavity gap Coordinate, upper surface connects with the level of " ladder " formula differential-velocity extrusion step 17 of the inner chamber of " u "-shaped lower cavity die 5, and lower surface is positioned over down On backing plate 6.The lower surface of jacking block 11 is provided with screwed hole, is threadedly coupled with described push rod 9.
Described drift 12, "T"-shaped upper cavity die 4, the through hole of " u "-shaped lower cavity die 5, push-rod hole, jacking block 11, push rod 9 On same axis;Mode flexible back and forth runs on the "T"-shaped upper cavity die 4, " u "-shaped of combination type under described push rod more than 9 In the through hole and the through hole of push rod 9 of lower cavity die 5.
Fig. 1, Fig. 2 are referred to, forcing press superstructure (not shown) is by fastening bolt 14 and upper die plate 1, lower mould Cover for seat 3 connects, and compression spring 13 is installed in fastening bolt 14, covers between 3 upper ends and upper die plate 1 positioned at die shoe.
Fig. 1, Fig. 2 are referred to, a kind of differential-velocity extrusion manufacturing process of magnesium alloy high-performance cup shell, its step includes:
(1) bar material baiting;
(2) homogenization heat treatment, forms magnesium alloy blank.
(3) the differential-velocity extrusion mould shown in Fig. 1, Fig. 2 is integrally preheated to into 30 DEG C~more than 50 DEG C of Mg alloy formed temperature Insulation 2h, and magnesium alloy blank is heated to into 350 DEG C of forming temperature and 2~4h is incubated.Differential-velocity extrusion mould is filled as shown in Figure 1 Fit on forcing press.
(4) bolt 14 that upper die plate 1 is connected with die shoe set 3, forcing press upper table slide block (not shown) are unclamped Rise and drive upper die component:Upper die plate 1, upper bolster set 2, drift 12 rises with slide block, makes drift 12 depart from combination type recessed The inner chamber of mould;From the beginning of the cylindrical cavity mouth of "T"-shaped upper cavity die 4 of combined die, certain oil preparation stone is injected toward inner chamber Black lubricant, and inject one toward " mountain " font extruding intracavity of combined die from the lubricant aperture of the upper end of "T"-shaped upper cavity die 4 Quantitative oil preparation graphitic lubricant;350 DEG C of magnesium alloy blanks after by Homogenization Treatments are put in the cylinder of "T"-shaped upper cavity die 4 In chamber;
(5) forcing press upper table slide block is moved downward, and drives drift 12 with the axially-movable speed pair of 0.5~5mm/s Magnesium alloy blank in combined die inner chamber is extruded, and makes magnesium alloy blank in " mountain " font extrusion chamber of combined die Flowing extruding, (as shown in Figure 1) in 16.Because the diameter of blank is less than the cylindrical cavity of "T"-shaped upper cavity die 4, thus in drift Under 12 pressure, there is at first the cylindrical cavity part of the full "T"-shaped upper cavity die 4 of Upsetting filling, the lower end of metal in metal Subsequently deform, as drift 12 continues to move downward, metal stock is finally filled in " mountain " font extrusion chamber 16.
(6) forcing press upper table slide block continues to move downward, until the magnesium alloy cup-shape member of size required for obtaining, Stop moving downward for forcing press upper table slide block.
(7) bolt 14 that upper die plate 1 is connected with die shoe set 3 is tightened, unclamps lower template 7 and cover 3 junctions with die shoe Fastening bolt;Forcing press upper table slide block (not shown) is moved back up, drive drift 12 move upwards and with The cup-shaped drip molding of magnesium alloy departs from, and fastening bolt 14 drives the "T"-shaped upper cavity die 4, " u "-shaped of die shoe set 3 and combined die Lower cavity die 5 departs from.
(8) push rod 9 is pushed up by the liftout tank (not shown) of hydraulic press, by the magnesium alloy cup of extrusion molding Shape drip molding and "T"-shaped upper cavity die 4 are ejected from the intracavity of " u "-shaped lower cavity die 5;"T"-shaped upper cavity die 4 is removed, and is attached it to The intracavity of " u "-shaped lower cavity die 5.
(9) forcing press upper table slide block is moved downward, and drives die shoe set 3 to move downward, to die shoe cover 3 bottoms with Lower bolster 6 is contacted, and is stopped forcing press upper table slide block and is moved downward, and the bolt that lower template 7 is connected with die shoe set 3 is twisted Tightly.
(10) repeating operation (4)~(9) can continuously complete the differential-velocity extrusion shaping of cup shell.
Embodiment:
To prepare the AZ31 magnesium alloy cups of external diameter 200mm internal diameter 170mm as instantiation.
The billet size for being adopted for H=360mm, diameter D1=80mm, the intracavity diameter D of "T"-shaped upper cavity die 42=90mm, D1< D2.Mould is integrally preheated to 400 DEG C of insulation 2h, and magnesium alloy blank is heated to 350 DEG C of forming temperature and is incubated 2~4h.Drift Extrusion speed is 1mm/s.
As shown in figure 3-1,4~8 vertical holes are opened up as being passed through lubrication the upper end of "T"-shaped upper cavity die 4 is isometrical vertically Agent aperture.
As shown in figure 3-2, the sizing strip length L2 of "T"-shaped upper cavity die 4 be 8.8mm, the sizing belt length of " u "-shaped lower cavity die 5 Degree L1 is 24mm;Consider from the extruding force angle for being conducive to metal flow as big as possible with offer, the lower end of "T"-shaped upper cavity die 4 Calibrating strap and horizontal bottom joint face are inclined-plane, and inclined-plane is in 45 ° with horizontal direction, "T"-shaped upper cavity die 4 and " u "-shaped lower cavity die 5 Annular boss 18 is connected with conduit wall with inclined-plane, and inclined-plane is 45 ° with vertical or horizontal channel wall angle, the height of boss For 5mm or so;The intracavity bottom roundings radius R=20mm of " u "-shaped lower cavity die 5, realizes that metal is produced in bottom roundings region to facilitate The big detrusion of life.The inclination angle of the not specified all intermediate inclines of " mountain " font extruding cavity wall is equal shown in Fig. 3-2 For 45 °.
Refer to Fig. 4-1, Fig. 4-1 for the bottom of " mountain " font extrusion chamber 16 " ladder " formula differential-velocity extrusion step 17, step Long a=6mm, high h=4mm, transitional radius r=4mm, step number value 3~4.From being conducive to metal in extrusion process In extrude forward one by one along step, and be unlikely to be formed dead angle, fold and fold etc. from the aspect of, adjacent horizontal bench The inclined-plane of junction adopts 45 ° with horizontal direction inclination angle size;Fig. 4-2 are referred to, the differential of the lower surface of "T"-shaped upper cavity die 4 is squeezed Present a theatrical performance as the last item on a programme rank 17 and the differential-velocity extrusion step 17 of the corresponding intracavity of " u "-shaped lower cavity die 5, in a longitudinal direction wrong potential difference, it is poor to misplace For length a/2=3mm of half step.The not specified all transition of " mountain " font extruding cavity wall are oblique shown in Fig. 3-2 The inclination angle in face is 45 °.
The design of above-mentioned " ladder " formula differential radial compression step, Main Function is to entering the bottom of " mountain " font die cavity 16 Metal apply extruding, change its stress state, increase deformation.Main efficacy results have three:
One is, metal when " ladder " formula radial direction differential squeeze station rank 17 is flowed through, the boss phase with differential-velocity extrusion step 17 Interaction, metal upper and lower surface is subject to the shear action of differential-velocity extrusion step 17;
Two are, " ladder " formula differential radial compression step is the little passage of entrance large outlet, the gold during extruding metal Belong to the Step Shaft extruding force effect upwards that can be squeezed;
Three are, upper and lower differential-velocity extrusion step has in the vertical a dislocation poor, and this dislocation is differed from during extruding metal not But increased the metal number of times of crimp repeatedly up and down, and because metal is contacted with Steps after, upper and lower surface is formed Current difference, so as to produce certain moment of torsion in metal inside so as to which inside is also acted on by shear stress.
" ladder " formula differential-velocity extrusion step 17 of the present invention, changes the stress state of metal, drastically increases extruding The amount of plastic deformation of metal.Because traditional backward extrusion technology cup shell microstructure is flat elongate grains, organize each to different Property it is larger, and the extrusion side wall crystal grain of circular passage corner extrusion technique is in bi-modal distribution, weakens the synthesis of extrusion Performance, and the design of " ladder " formula differential-velocity extrusion step of the present invention, have greatly crushed elongated big crystal grain, make CRYSTALLITE SIZES Refinement is more uniformly distributed, obvious to eliminating crystal grain bi-modal distribution effect.
Fig. 5 is referred to, Fig. 5 is metal flow subregion schematic diagram during present invention extruding flow of metal.Magnesium alloy blank is being justified In the presence of Columnar punch pressure, through the deformation of three phases:One is through the axially upset deformation stage of similar cylinder;Two are The radial compression large deformation stage.With forcing press drive drift 12 continue to be pressed down against, metal start along " mountain " font squeeze The pressure bottom radial compression of chamber 16, enters " ladder " formula differential radial compression area;During this, metal undergauge after differential-velocity extrusion band It is squeezed into the less squeezing passage of internal diameter;Three is the corner extrusion detrusion stage.With forcing press drive drift continue to Lower extruding, metal is changed into axial flowing in fillet deformed area metal from Radial Flow, and great detrusion occurs.
The present invention compared with magnesium alloy cup shell conventional extruded method and circular passage corner extrusion manufacturing process, with Lower beneficial effect:
(1) crystallized ability of magnesium alloy is improved.Magnesium alloy is inductile material, is even shaped at high temperature, also easily Cracking." mountain " font extrusion chamber of the present invention effectively increases the inside hydrostatic pressure of extrusion, and pole increases substantially magnesium alloy The plasticity of material.
(2) high compact texture is obtained, grain refinement effect is more notable, obtains bigger average equivalent strain, working hardening effect It is really more significantly." mountain " font extrusion chamber bottom " ladder " formula differential-velocity extrusion step of the present invention has increased considerably metal in " rank The number of times of ladder " formula differential radial compression area crimp repeatedly, make metal in flow process repeatedly with " ladder " formula of dislocation There is reciprocal action in differential-velocity extrusion step, make surface be subject to more shearing forces and axial compression power with internal, change magnesium conjunction Golden material internal stress state so as to produce great deflection.Metal experiences " ladder " formula differential-velocity extrusion area and subsequent bottom Behind fillet detrusion area of portion, can the internal void of seam extrusion of high degree, portion's as-cast structure in breaking deformation body, thin Change crystal grain to submicron and or even nanoscale, form high-angle boundary structure, obtain high compact texture, magnesium alloy is greatly enhanced The working hardening effect of material.
(3) to eliminating crystal grain bi-modal distribution effect substantially, profiled member barrel mixing tension failure mechanism is effectively reduced Incidence rate.Traditional backward extrusion cup shell barrel microstructure is the elongate grains for elongating, and anisotropy is more apparent.Circular passage turns The cup shell barrel crystal grain that angle is extruded from is in bi-modal distribution, and the plasticity and mechanical property of cups are reduced to a certain extent Energy.The present invention is extruded and crushed repeatedly for these deficiencies of above-mentioned technique by " ladder " the formula differential-velocity extrusion step for misplacing Coarse grain and the elongate grains being elongated, so as to barrel radial direction crystal grain bi-modal distribution is greatly reduced, effectively improve cup The comprehensive mechanical property of shape component.
(4) technological parameter controllability is strong, can squeeze out the magnesium alloy cup-shape member of different performance requirement and specification.Pass through The technological parameter of control " ladder " formula differential-velocity extrusion step:Step number, step length to height ratio a/h, intermediate zone inclination alpha are changing magnesium Stressing conditions of the alloy blank in extrusion process used for forming, so as to control metal stresses state, equivalent strain amount, crystal grain refinement journey Degree, plastic deformation and structural homogenity etc..
(5) Making programme of high-performance magnesium-alloy cup shell is shortened:Traditional backward extrusion high-performance magnesium-alloy is cup-shaped Before part, blank is slender cylinder, it is necessary to by the rough base of multi-pass cylinder pier, and the present invention can direct extrusion molding ratio of height to diameter There is no unstability bending more than 3 blank, so as to eliminate upset operation.Directly utilize axial compressive force, radial pressure and cut Great plastic deformation is achieved with to the collective effect of shearing force, contributes to break down dendritic tissue and impurity, significantly carried High magnesium alloy materials working hardening effect, obtains hardness height, and anisotropy is little, organizes relatively uniform, and crystal grain is significantly refined, comprehensive The more excellent high-performance magnesium-alloy cup shell of mechanical property.
(6) it is simulated by Deform-3D Finite Element Simulation Softwares and is contrasted, demonstrates the new differential-velocity extrusion of the present invention Cup shell is obtained in that bigger amount of plastic deformation, has more metals that the stream of more large deformation is participated in plastic history It is dynamic.Analog parameter setting aspect, what material was imported is the parameter model of AZ80, and temperature is 380 DEG C, and stress and strain model is 20000, punching Head speed is 1mm/s, and coefficient of friction is 0.25.Can visually see from analog result, the shaping of circular passage corner extrusion Cup shell average equivalent strain value (AVG) is 4.01, and the new differential extrusion cup shape part average equivalent strain value of the present invention (AVG) 4.89 are up to, it is clear that the average equivalent strain value of the new differential extrusion cup shape part of the present invention is noticeably greater than circular passage Corner extrusion.So as to cup shell prepared by the new differential pressing method confirmed by the present invention is obtained in that bigger plasticity Deflection.From the degree aspect of deformation, can intuitively observe from cloud atlas, the barrel outer wall of differential-velocity extrusion and the color of inwall It is almost consistent, and circular passage corner extrusion is then to be gradually lowered from outside to inside.This explanation multi-ladder differential-velocity extrusion into Shape method can make metal " squeeze saturating " in plastic history, that is to say, that can make metal as much as possible in plastic deformation During participate in the flowing of more large deformation.
(7) by experiment and microscopic examination contrast, the new differential extrusion forming method for demonstrating the present invention is offseted Except crystal grain bi-modal distribution effect it is obvious.Be respectively adopted circular passage corner extrusion manufacturing process and the present invention differential-velocity extrusion into Shape method is obtained the AZ31 magnesium alloy cups (tool that above-mentioned specific embodiment part adopts of external diameter 200mm internal diameter 170mm Body example), profiled member is dissected, face (sample bottom end face) of the barrel position perpendicular to metal flow direction of materialsing respectively Microstructure observation is carried out under Zeiss metallurgical microscope, Fig. 7, Fig. 8 are respectively circular passage corner extrusion shaping, new differential Face metallographic microstructure photo of the cup shell barrel position of extrusion molding perpendicular to metal flow direction.From metallographic microstructure Photo can visually see, using the cup shell barrel position crystal grain bi-modal distribution after new differential extrusion forming method Phenomenon is substantially eliminated.
(8) present invention provides the strong manufacture method of a kind of short route, high-performance, controllability for magnesium alloy cup-shape member, Reference is provided to prepare Ultra-fine Grained high-performance cup shell.With the light weight of the equipments such as Aero-Space, defence and military, transportation Change level is improved, and the war skill index request such as speed, reliability, bearing capacity is also increasingly lifted, bearing capacity high to hardness be strong, The demand of the tissue Ultra-fine Grained high-performance magnesium-alloy cup shell that relatively uniform, anisotropy is little, comprehensive mechanical property is more excellent Increasing, combination property requires more and more higher, and application prospect of the present invention will become better and better.
It is obvious to a person skilled in the art that the invention is not restricted to the details of above-mentioned one exemplary embodiment, Er Qie In the case of spirit or essential attributes without departing substantially from the present invention, the present invention can be in other specific forms realized.Therefore, no matter From the point of view of which point, embodiment all should be regarded as exemplary, and be nonrestrictive, the scope of the present invention is by appended power Profit is required rather than described above is limited, it is intended that all in the implication and scope of the equivalency of claim by falling Change is included in the present invention.
Moreover, it will be appreciated that although this specification is been described by according to embodiment, not each embodiment is only wrapped Containing an independent technical scheme, this narrating mode of description is only that for clarity those skilled in the art should Using description as an entirety, the technical scheme in each embodiment can also Jing it is appropriately combined, form those skilled in the art Understandable other embodiment.

Claims (1)

1. a kind of differential-velocity extrusion manufacturing process of magnesium alloy high-performance cup shell, it is characterised in that:Comprise the following steps:
(1) bar material baiting;
(2) homogenization heat treatment, forms magnesium alloy blank;
(3) prepare before shaping:Magnesium alloy blank is heated to into forming temperature and is incubated, and differential-velocity extrusion shaping dies are overall pre- Heat is to more than magnesium alloy blank forming temperature and is incubated;Described differential-velocity extrusion shaping dies include the superstructure with forcing press The mold component of connection and the lower die assembly and combined die of the connection of forcing press substructure;Described mold Component includes that the upper bolster that the upper die plate being connected with the upper table of forcing press connects with upper die plate covers and upper bolster set is built-in Drift;Described upper die plate fastening bolt is assemblied on forcing press upper table, and the upper ends of the drift are in upper mould On the inside center line of cover for seat, drift upper end is covered upper bolster and upper die plate by cylinder finger setting, surrounding by hexagon socket head cap screw It is fixed, drift is firmly anchored in upper bolster set;Described combined die includes that "T"-shaped upper cavity die and " u "-shaped are recessed Mould, described "T"-shaped upper cavity die inside is cylindrical mold cavity, is coordinated with drift gap, and "T"-shaped upper cavity die upper end is provided with annular cone The spacing cooperation of end cone face on face, with die shoe set die cavity;Described " u "-shaped lower cavity die inside is revolving body die cavity;"T"-shaped fovea superior Mould is arranged in the revolving body die cavity of " u "-shaped lower cavity die, and the cross sectional shape that revolving body die cavity and cylindrical mold cavity are collectively constituted is " mountain " font extrusion chamber;Described lower die assembly includes lower template cover for seat, lower bolster and lower template;In described die shoe set Portion is cylindrical mold cavity, and die cavity inside coordinates with combined die gap, and die cavity upper end is closed up with circular cone, with to upper cavity die Spacing load;Die shoe covers and lower bolster is fixed on from top to bottom in lower template.
(4), installation mold:By the mould installion after preheating insulation on forcing press;Oil preparation stone is injected to combined die inner chamber Black lubricant, while from fovea superior die tip aperture from top to bottom toward " mountain " font extruding intracavity injection oil preparation graphitic lubricant;Will The upper cavity die cylindrical type intracavity of combined die is put into through the magnesium alloy blank of homogenization heat treatment;
(5) forming process:Forcing press drives the upper die plate of mold component, upper bolster set and drift to move downward, and extruding magnesium is closed Golden blank extrudes intracavity along die cavity flow deformation in " mountain " font;Magnesium alloy blank in the presence of cylindrical punch pressure, Jing Cross the deformation of three phases:One is through the axially upset deformation stage of similar cylinder;Two is the radial compression large deformation stage;With Forcing press drives drift to continue to be pressed down against, and metal starts along " mountain " font extrusion chamber bottom radial compression, during this, metal Flow through undergauge after differential-velocity extrusion band and be squeezed into the less squeezing passage of internal diameter;Three is the corner extrusion detrusion stage;Pressure Machine drives drift to continue to be pressed down against metal into " mountain " font extrusion chamber bottom roundings region, and metal receives shear stress edge Die wall to flow axially upwards, form the barrel of magnesium alloy cup shell;
(6) after the completion of extrusion molding:Stop moving downward for forcing press upper table;Tighten what upper die plate was connected with die shoe set Fastening bolt, unclamps the fastening bolt of die shoe set, lower bolster and lower template junction;Forcing press upper table is transported back up It is dynamic, drive drift to rise and depart from cup shell, while upper die plate drives die shoe set to rise, depart from combined die;It is logical Cross hydraulic cylinder liftout tank to act on push rod, magnesium alloy cup shell is ejected from combined die.
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