CN106607468B - A kind of differential-velocity extrusion manufacturing process of magnesium alloy high-performance cup shell - Google Patents

A kind of differential-velocity extrusion manufacturing process of magnesium alloy high-performance cup shell Download PDF

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CN106607468B
CN106607468B CN201710024674.9A CN201710024674A CN106607468B CN 106607468 B CN106607468 B CN 106607468B CN 201710024674 A CN201710024674 A CN 201710024674A CN 106607468 B CN106607468 B CN 106607468B
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die
cavity
extrusion
shaped
differential
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CN106607468A (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

A kind of differential-velocity extrusion manufacturing process of magnesium alloy high-performance cup shell, is related to Metal Forming forming technique field;Using combined die, including "T"-shaped upper cavity die and " u "-shaped lower cavity die.It is cylinder cavity inside "T"-shaped upper cavity die, "T"-shaped upper cavity die is mounted on " u "-shaped lower cavity die, and the section of the revolving body cavity of formation is " mountain " font.The bottom of " mountain " font extrusion chamber is using " ladder " formula differential-velocity extrusion step to misplace.By the deformation of three phases:First, by the upset deformation stage of axial similar cylinder;Second is that the radial compression large deformation stage;Third, the corner extrusion detrusion stage." ladder " the formula differential-velocity extrusion step to be misplaced using " mountain " font extrusion chamber and bottom of chamber is come extrusion magnesium alloy cup shell, greatly improve magnesium alloy materials crystallized ability, obtain high compact texture, great amount of plastic deformation, grain refining effect is notable, it is with obvious effects to eliminate the crystal grain bi-modal distribution of cup shell barrel, shortens high-performance magnesium-alloy cup shell production process.

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 fields, and in particular to one kind is squeezed for magnesium alloy materials Pressing formation and modified differential-velocity extrusion manufacturing process.
Background technology
Cup-shape member is one of most representative structure type in the fields such as aerospace, defence and military, communications and transportation, is The typical product of reversal extrusion technique.It is manufactured for cup shell, mostly using backward extrusion technology, reversal extrusion technique is one The advanced machining process with less cutting of kind, not only increases the form and dimensional precision of forging, has saved metal material, and because of gold Belong to fibre flow and improve the mechanical performance of such part in profiling, there is " efficient, high-quality, low energy consumption ", Technology and economically there is very high use value, it has also become fall over each other the hot spot of research both at home and abroad.
Magnesium alloy cup shell is using the method for traditional backward extrusion, it is necessary to which multi-pass jumping-up pulling base reaches preferable Refined crystalline strengthening effect, low production efficiency and formed parts anisotropy is apparent, the tensile strength difference of circumferential and axial are larger. Therefore, researching and developing the new manufacturing process of magnesium alloy with high strength and ductility cups has 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 scope, There is very big technical advantage compared to traditional backward extrusion method, the average equivalent plastic strain of drip molding is up to traditional backward extrusion 2 times or more, plastic force is small, and deflection is big, and the distribution of the equivalent plastic strain of drip molding is more uniform, brilliant for cup-shape member Grain refinement has certain effect with the promotion of mechanical property tool and effect.
But the study found that by patent " the circular passage corner extrusion shaping dies and method of magnesium alloy cup-shape member " into The cup shell of shape, for barrel on the face in metal flow direction, crystal grain is in representative dual-mode state crystal grain distribution.Bimodal crystal grain Distribution refers to that metal is crushed elongations under the action of extrusion chamber inner conical boss, and the original coarse grain in part obtains significantly carefully Change, the coarse crystal grain in part is distributed in strip.Crystal grain distribution form is very much like afterwards with Equal-channel Angular Pressing (ECAP) for this. The bi-modal distribution phenomenon of crystal grain causes cup shell barrel sample axial tension fracture mechanism adjoint for the ductile rupture of fine grain band The mixed fracture mechanism that the Brittle cleavage fracture of coarse region is combined reduces the plasticity and mechanical property of cups to a certain extent Energy.Obviously, barrel crystal grain bi-modal distribution restricts high tough cup shell research and development and production practices.With regard to this apparently, " magnesium closes patent There are certain technical limitations for the circular passage corner extrusion shaping dies and method of golden cup-shape member ".
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, this method can be come The average equivalent strain of bigger is obtained, grain refining effect is improved, significantly reduces the cupuliform of circular passage corner extrusion shaping The barrel of part is in bimodal crystal grain distribution, reduces the incidence of barrel mixing tension failure mechanism.
In order to solve the problems existing in background technology, the present invention adopts the following technical solutions:
A kind of differential-velocity extrusion manufacturing process of magnesium alloy high-performance cup shell, order include:
(1) bar material baiting;
(2) homogenization heat treatment forms magnesium alloy blank;
(3) prepare before shaping:Magnesium alloy blank is heated to forming temperature and is kept the temperature, and differential-velocity extrusion shaping dies is whole Body is preheated to more than magnesium alloy blank forming temperature and keeps the temperature;The differential-velocity extrusion shaping dies includes the top with forcing press The mold component of structure connection, the lower die assembly and combined die being connected with forcing press substructure;Described is upper Die assembly includes the cope plate being connected with the upper table of forcing press, the upper mold cover for seat to connect with cope plate and upper mold cover for seat Built-in punch;The cope plate is assemblied in fastening bolt on forcing press upper table, and the upper ends of the punch exist On the inside center line of upper mold cover for seat, punch upper end by cylinder finger setting, surrounding by hexagon socket head cap screw upper mold cover for seat with it is upper Template is fixed, and punch is made firmly to be anchored in upper mold cover for seat;The combined die includes, under "T"-shaped upper cavity die and " u "-shaped Cavity plate, "T"-shaped upper cavity die inside are cylindrical mold cavity, and with punch clearance fit, "T"-shaped upper cavity die upper end is equipped with annular End cone face /V coordinates on the conical surface, with lower die cover for seat cavity;It is revolving body cavity inside the " u "-shaped lower cavity die;On "T"-shaped Cavity plate is mounted in the revolving body cavity of " u "-shaped lower cavity die, the cross sectional shape that revolving body cavity and cylindrical mold cavity collectively constitute For " mountain " font extrusion chamber;The lower die assembly includes lower template cover for seat, lower bolster and lower template;The lower die cover for seat Inside is cylindrical mold cavity, cavity inside and combined die clearance fit, and cavity upper end is closed up with circular cone, with to fovea superior Mould /V load;Lower die cover for seat and lower bolster are fixed in lower template from top to bottom.
(4), installation mold:Mold after preheating insulation is mounted on forcing press;Oil is injected to combined die inner cavity Agent graphitic lubricant, while finish graphite lubrication is injected in " mountain " font extrusion chamber from top to bottom from fovea superior die tip aperture Agent;The upper cavity die cylindrical type intracavitary of combined die will be put by the magnesium alloy blank of homogenization heat treatment;
(5) forming process:Forcing press drives cope plate, upper mold cover for seat and the punch of mold component to move downward, and squeezes Magnesium alloy blank is in " mountain " font extrusion chamber along cavity flow deformation;Magnesium alloy blank is in the effect of cylindrical punch pressure Under, by the deformation of three phases:First, by the upset deformation stage of axial similar cylinder;Second is that radial compression large deformation rank Section;As forcing press drives punch to continue to be pressed down against, metal starts along " mountain " font extrusion chamber bottom radial compression, this process In, undergauge is squeezed into the smaller squeezing passage of internal diameter after metal flows through differential-velocity extrusion band;Third, corner extrusion detrusion rank Section;Forcing press drives punch 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 cavity plate wall, forms the barrel of magnesium alloy cup shell;
(6) after the completion of extrusion molding:Stop moving downward for forcing press upper table;Cope plate is tightened with lower die cover for seat to connect The fastening bolt connect unclamps lower die cover for seat, lower bolster and the fastening bolt of lower template junction;Forcing press upper table reversely to Upper movement drives punch to rise and depart from cup shell, while cope plate drives die holder set to rise, and is taken off with combined die From;Mandril is acted on by hydraulic cylinder liftout tank, magnesium alloy cup shell is ejected from combined die.
The principle of the present invention is:Devise combined die structure, "T"-shaped fovea superior mold cavity and the recessed mold cavity of " u "-shaped " mountain " shaped rotary build chamber is collectively formed, particularly cavity bottom employs " ladder " formula differential-velocity extrusion step.The length of step It spends for a, a height of h, neighbouring step transition band level inclination is α, transitional radius r.So-called differential refers to "T"-shaped " ladder " step of upper cavity die lower face is with " ladder " step of the recessed mold cavity of the " u "-shaped of corresponding lower position in longitudinal direction Have that dislocation is poor, and 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 uses the upper and lower longitudinally displaced distance of " ladder " step as half of length of bench a/2 (by Deform-3D finite element modellings, average equivalent plastic strain is maximum when dislocation distance is a/2).
By the way that technological parameter (step number, step length to height ratio a/h, intermediate zone inclination alpha) is controlled to change magnesium alloy blank 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..After metal flows through " ladder " formula differential-velocity extrusion step, metal upper and lower surface be squeezed step shearing The effect of stress;Simultaneously because " ladder " formula radial compression step has a dislocation poor up and down, cause metal in this Regional contraction Upper and lower surface extrusion speed is inconsistent, and metal inside can also generate torque and shear stress;In addition, " staged " radial compression step The crush-zone formed is big for inlet calibre, and outlet bore is small, and metal is also subject to " staged " when being squeezed into this region Radial compression step axial direction extruding force.
These three factors change the stress state of metal jointly, cause metal surface and inside that can obtain bigger plasticity Deflection adds average equivalent strain, obtains higher compact texture, tissue thinning effect is notable, " staged " radial compression Step effectively increases deforming degree of the metal in extrusion process, and it is microcosmic significantly to have crushed traditional backward extrusion technology cup shell Flat elongate strip distribution is organized as, more uniformly spreads CRYSTALLITE SIZES, it is bright to eliminating crystal grain bi-modal distribution phenomenon effect It is aobvious.
Description of the drawings
It in order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing There is attached drawing needed in technology description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this Some embodiments of invention, for those of ordinary skill in the art, without creative efforts, can be with Other attached drawings are obtained according to these attached 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 to misplace 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 provided by the present invention shaping;
Reference numeral:
1- cope plates;2- upper mold cover for seat;3- lower die cover for seat;The "T"-shaped upper cavity dies of 4-;5- " u "-shaped lower cavity dies;6- lower bolsters; 7- lower templates;8- straight pins;9- mandrils;10- screws;11- jacking blocks;12- punches;13- compresses spring;14- fastening bolts;15- Vertical direction hole;16- " mountain " font extrusion chamber;17- differential-velocity extrusion steps;18- annular convex platform.
Specific embodiment
In order to make the purpose , technical scheme and advantage of the present invention be clearer, below in conjunction with attached drawing and specific implementation Mode, the present invention will be described in further detail.It should be appreciated that the specific embodiments described herein are only explaining this Invention, is not intended to limit the present invention.
- Fig. 6 is please referred to Fig.1, present embodiment uses following technical scheme: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 are connected with forcing press substructure Lower die assembly and combined die.
- Fig. 2 is please referred to Fig.1, the mold component includes:The cope plate 1 that is connected with the superstructure of press, with it is upper The punch 12 built in upper mold cover for seat 2 and upper mold cover for seat that template 1 connects.The upper ends of the punch 12 are in upper mold cover for seat 2 Inside center.
Refer to Fig. 3-1, the combined die, including "T"-shaped upper cavity die 4 and " u "-shaped lower cavity die 5." T " 4 inside of shape upper cavity die is cylindrical mold cavity, and with 12 clearance fit of punch, "T"-shaped 4 upper end of upper cavity die is equipped with circular cone, under Die holder covers end cone face /V cooperation on 3 cavities.5 inside of " u "-shaped lower cavity die is revolving body cavity."T"-shaped upper cavity die 4 is pacified In the revolving body cavity of " u "-shaped lower cavity die 5, the cross sectional shape that cylindrical mold cavity and revolving body cavity collectively constitute is " mountain " Font extrusion chamber 16;"T"-shaped 4 upper end of upper cavity die in axial direction sets 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 is also provided with " ladder " formula differential-velocity extrusion step 17 in the mold cavity surface of " u "-shaped lower cavity die 5.It is "T"-shaped 4 outside lower end of upper cavity die is set there are one annular convex platform, is the extruding calibrating strap of cup shell internal diameter.Corresponding lateral position, One section of annular convex platform is equally provided in 5 cavity of " u "-shaped lower cavity die, is the extruding calibrating strap of cup shell outer diameter, which determines Footpath band and the tangent connection of " u "-shaped lower cavity die cavity bottom fillet.
It please refers to Fig.1, Fig. 2, the lower die assembly includes lower die cover for seat 3, lower bolster 6 and lower template 7, under described 3 inside of die holder set is cylindrical mold cavity, is closed up inside cavity with combined die clearance fit, cavity upper end with circular cone, With to "T"-shaped 4 /V load of upper cavity die;Lower die cover for seat 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 lower die is fixed on from top to bottom with screw 10 On plate 7.
The lower bolster 6 and 7 middle part of lower template is equipped with and knockdown "T"-shaped upper cavity die 4,5 bottom of " u "-shaped lower cavity die The push-rod hole that through hole communicates, the jacking block 11 are placed in the inner cavity of combined type " u "-shaped lower cavity die 5, with interior cavity gap Cooperation, upper surface connect with 17 level of " ladder " formula differential-velocity extrusion step of 5 inner cavity of " u "-shaped lower cavity die, and lower surface is positioned over down On backing plate 6.The lower surface of jacking block 11 is provided with threaded hole, is threadedly coupled with the mandril 9.
The punch 12, "T"-shaped upper cavity die 4, the through hole of " u "-shaped lower cavity die 5, push-rod hole, jacking block 11, mandril 9 On same axis;Mode flexible back and forth runs on the "T"-shaped upper cavity die 4 of combined type, " u "-shaped under the mandril more than 9 In 9 through hole of through hole and mandril of lower cavity die 5.
It please refers to Fig.1, Fig. 2, forcing press superstructure (not shown) passes through fastening bolt 14 and cope plate 1, lower die Cover for seat 3 connects, the installation compression spring 13 in fastening bolt 14, between 3 upper end of lower die cover for seat and cope plate 1.
It please refers to Fig.1, Fig. 2, a kind of differential-velocity extrusion manufacturing process of magnesium alloy high-performance cup shell, step includes:
(1) bar material baiting;
(2) homogenization heat treatment forms magnesium alloy blank.
(3) Fig. 1, differential-velocity extrusion mold shown in Fig. 2 are integrally preheated to Mg alloy formed 30 DEG C~50 DEG C or more of temperature 2h is kept the temperature, and magnesium alloy blank is heated to 350 DEG C of forming temperature and keeps the temperature 2~4h.Differential-velocity extrusion mold is filled as shown in Figure 1 It fits on forcing press.
(4) bolt 14 that cope plate 1 is connected with lower die cover for seat 3, forcing press upper table sliding block (not shown) are unclamped Rise and drive upper die component:Cope plate 1, upper mold cover for seat 2, punch 12 rise with sliding block, punch 12 are made to depart from combined type recessed The inner cavity of mould;Since the 4 cylindrical cavity mouth of "T"-shaped upper cavity die of combined die, certain finish stone is injected into inner cavity Black lubricant, and one is injected in " mountain " font extrusion chamber of combined die from the lubricant aperture of "T"-shaped 4 upper end of upper cavity die Quantitative finish graphitic lubricant;350 DEG C of magnesium alloy blanks after Homogenization Treatments are put into "T"-shaped 4 cylinder of upper cavity die In chamber;
(5) forcing press upper table sliding block moves downward, and drives punch 12 with the axial movement speed pair of 0.5~5mm/s Magnesium alloy blank in combined die inner cavity is squeezed, and makes magnesium alloy blank in " mountain " font extrusion chamber of combined die Flowing squeezes in 16, (as shown in Figure 1).Since the diameter of blank is less than "T"-shaped 4 cylindrical cavity of upper cavity die, thus in punch Under 12 pressure, the cylindrical cavity part of the full "T"-shaped upper cavity die 4 of Upsetting filling, the lower end of metal occur at first for metal It then deforms, as punch 12 continues to move downward, metal stock is finally filled in " mountain " font extrusion chamber 16.
(6) forcing press upper table sliding 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 sliding block.
(7) bolt 14 that cope plate 1 is connected with lower die cover for seat 3 is tightened, unclamps lower template 7 and 3 junction of lower die cover for seat Fastening bolt;Forcing press upper table sliding block (not shown) moves back up, drive punch 12 move upwards and with Magnesium alloy cupuliform drip molding departs from, and fastening bolt 14 drives the "T"-shaped upper cavity die 4 of lower die cover for seat 3 and combined die, " u "-shaped Lower cavity die 5 departs from.
(8) mandril 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 intracavitary of " u "-shaped lower cavity die 5;"T"-shaped upper cavity die 4 is removed, and is attached it to 5 intracavitary of " u "-shaped lower cavity die.
(9) forcing press upper table sliding block moves downward, and lower die cover for seat 3 is driven to move downward, until 3 bottom of lower die cover for seat with Lower bolster 6 contacts, and stops forcing press upper table sliding block and moves downward, lower template 7 is twisted with the bolt that lower die cover for seat 3 is connected Tightly.
(10) the differential-velocity extrusion shaping of cup shell can continuously be completed by repeating process (4)~(9).
Embodiment:
To prepare the AZ31 magnesium alloys cups of outer diameter 200mm internal diameters 170mm as specific example.
Used billet size is H=360mm, diameter D1=80mm, "T"-shaped 4 intracavity diameter D of upper cavity die2=90mm, D1< D2.Mold is integrally preheated to 400 DEG C of heat preservation 2h, and magnesium alloy blank is heated to 350 DEG C of forming temperature and keeps the temperature 2~4h.Punch Extrusion speed is 1mm/s.
As shown in figure 3-1,4~8 vertical holes are opened up as being passed through lubrication "T"-shaped 4 upper end of upper cavity die 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 metal flow is conducive to providing extruding force angle as big as possible, "T"-shaped 4 lower end of upper cavity die Calibrating strap and horizontal bottom joint face are inclined-plane, inclined-plane and horizontal direction in 45 °, "T"-shaped upper cavity die 4 and " u "-shaped lower cavity die 5 Annular convex platform 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;5 intracavitary bottom roundings radius R=20mm of " u "-shaped lower cavity die realizes that metal produces in bottom roundings region to facilitate Raw big detrusion.The inclination angle that " mountain " font shown in Fig. 3-2 squeezes the not specified all intermediate inclines of cavity wall is equal For 45 °.
Refer to Fig. 4-1, Fig. 4-1 is " ladder " formula differential-velocity extrusion step 17 of 16 bottom of " mountain " font extrusion chamber, step Long a=6mm, high h=4mm, transitional radius r=4mm, step number value 3~4.From metal is conducive in extrusion process In squeezed forward one by one along step, and be unlikely to form dead angle, folding and fold etc. consideration, adjacent horizontal bench The inclined-plane of junction uses 45 ° with horizontal direction inclination angle size;Fig. 4-2 are referred to, the differential of "T"-shaped 4 lower face of upper cavity die squeezes It presents a theatrical performance as the last item on a programme differential-velocity extrusion step 17 of the rank 17 with corresponding 5 intracavitary of " u "-shaped lower cavity die, in a longitudinal direction wrong potential difference, dislocation is poor For the length a/2=3mm of half of step.It is oblique that " mountain " font shown in Fig. 3-2 squeezes the not specified all transition of cavity wall The inclination angle in face is 45 °.
The design of above-mentioned " ladder " formula differential radial compression step, main function are to entering 16 bottom of " mountain " font cavity Metal apply and squeeze, change its stress state, increase deformation.Main efficacy results have three:
First, metal is when flowing through " ladder " formula radial direction differential squeeze station rank 17, the boss phase with differential-velocity extrusion step 17 Interaction, metal upper and lower surface are subject to the shearing force of differential-velocity extrusion step 17;
Second is that " ladder " formula differential radial compression step is the small passage of entrance large outlet, it is golden during extruding metal The upward extruding force effect of Step Shaft can be squeezed by belonging to;
Third, upper and lower differential-velocity extrusion step has in the longitudinal direction, dislocation is poor, this dislocation it is poor during extruding metal not But add the metal number of crimp repeatedly up and down, and because metal contacts with Steps after, upper and lower surface is formed Current difference so as to generate certain torque in metal inside, makes also shear stress to be subject to act on inside it.
" 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.Since traditional backward extrusion technology cup shell microstructure is flat elongate grains, tissue is each to different Property it is larger, and the extrusion side wall crystal grain of circular passage corner extrusion technique weakens the synthesis of extrusion in bi-modal distribution Performance, and the design of " ladder " formula differential-velocity extrusion step of the present invention, have greatly crushed elongated big crystal grain, have made CRYSTALLITE SIZES Refinement is more uniformly distributed, with obvious effects to eliminating crystal grain bi-modal distribution.
Referring to Fig. 5, metal flow subregion schematic diagram when Fig. 5 squeezes flow of metal for the present invention.Magnesium alloy blank is in circle Under the action of Columnar punch pressure, by the deformation of three phases:First, by the upset deformation stage of axial similar cylinder;Second is that The radial compression large deformation stage.As forcing press drives punch 12 to continue to be pressed down against, metal starts to squeeze along in " mountain " font 16 bottom radial compression of chamber is pressed, into " ladder " formula differential radial compression area;During this, metal passes through undergauge after differential-velocity extrusion band It is squeezed into the smaller squeezing passage of internal diameter;Third, the corner extrusion detrusion stage.With forcing press drive punch continue to Lower extruding, metal are 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, have with Lower advantageous 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 the strain of bigger average equivalent, working hardening effect Fruit is more notable." mountain " font extrusion chamber bottom " ladder " formula differential-velocity extrusion step of the present invention has increased considerably metal in " rank The number of ladder " formula differential radial compression area crimp repeatedly makes metal " ladder " formula with dislocation repeatedly in flow process Reciprocation occurs for differential-velocity extrusion step, and surface is made to be subject to more shearing forces and axial compression power with inside, changes magnesium conjunction Golden material internal stress state makes it generate great deflection.Metal undergoes " ladder " formula differential-velocity extrusion area and subsequent bottom It, can the internal void of soldering extrusion of high degree, as-cast structure inside breaking deformation body, thin behind fillet detrusion area of portion Change crystal grain to sub-micron and even nanoscale, formed high-angle boundary structure, obtain high compact texture, magnesium alloy be greatly enhanced The working hardening effect of material.
(3) it is with obvious effects to eliminating crystal grain bi-modal distribution, effectively reduce molded part barrel mixing tension failure mechanism Incidence.Traditional backward extrusion cup shell barrel microstructure is the elongate grains elongated, and anisotropy is more apparent.Circular passage turns The cup shell barrel crystal grain that angle is extruded from is in bi-modal distribution, reduces the plasticity and mechanical property of cups to a certain extent Energy.The present invention is squeezed and crushed repeatedly by " ladder " formula differential-velocity extrusion step of dislocation for these deficiencies of above-mentioned technique Coarse grain and the elongate grains being elongated so as to which barrel radial direction crystal grain bi-modal distribution be 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 Control the technological parameter of " ladder " formula differential-velocity extrusion step:Step number, step length to height ratio a/h, intermediate zone inclination alpha change 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) production process of high-performance magnesium-alloy cup shell is shortened:Traditional backward extrusion high-performance magnesium-alloy cupuliform Before part, blank is slender cylinder, it is necessary to which by the crude base of multi-pass cylinder pier, the present invention can direct extrusion molding ratio of height to diameter Blank more than 3 is bent without unstability, so as to eliminate upset process.Directly using axial compressive force, radial pressure and cut It is achieved with greatly being plastically deformed to the collective effect of shearing force, contributes to break down dendritic tissue and impurity, significantly carry High magnesium alloy materials working hardening effect obtains hardness height, and anisotropy is small, and tissue is relatively uniform, and crystal grain significantly refines, comprehensive The more excellent high-performance magnesium-alloy cup shell of mechanical property.
(6) simulation comparison is carried out by Deform-3D Finite Element Simulation Softwares, demonstrates the new differential-velocity extrusion of the present invention Cup shell can obtain the amount of plastic deformation of bigger, there is the stream that more metals participate in more large deformation in plastic history It is dynamic.In terms of analog parameter setting, what material imported is the parameter model of AZ80, and temperature is 380 DEG C, mesh generation 20000, punching Head speed be 1mm/s, coefficient of friction 0.25.It 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 new differential extrusion cup shape part of the invention is noticeably greater than circular passage Corner extrusion.So as to which cup shell prepared by the new differential pressing method confirmed through the present invention can obtain the plasticity of bigger Deflection.It in terms of the degree of deformation, can intuitively be observed from cloud atlas, the barrel outer wall of differential-velocity extrusion and the color of inner wall It is almost consistent, and circular passage corner extrusion is then to continuously decrease from outside to inside.This illustrate the differential-velocity extrusion of multi-ladder into Shape method can be such that metal " is squeezed saturating " in plastic history, that is to say, that can be plastically deformed metal as much as possible The flowing of more large deformation is participated in the process.
(7) compared by experiment and microscopic examination, the new differential extrusion forming method for demonstrating the present invention offsets Except crystal grain bi-modal distribution is with obvious effects.Be respectively adopted circular passage corner extrusion manufacturing process and the present invention differential-velocity extrusion into The AZ31 magnesium alloys cups (tool that above-mentioned specific embodiment part uses of outer diameter 200mm internal diameters 170mm is made in shape method Body example), molded part is dissected, and barrel position of materialsing respectively is perpendicular to the face in metal flow direction (sample bottom end face) Microstructure observation is carried out under Zeiss metallographic microscope, Fig. 7, Fig. 8 are respectively circular passage corner extrusion shaping, new differential The cup shell barrel position of extrusion molding is perpendicular to the face metallographic microstructure photo in 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 substantially eliminates.
(8) present invention provides the strong manufacturing 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 aerospace, defence and military, communications and transportation Change it is horizontal improve, the war skill index request such as speed, reliability, bearing capacity is also increasingly promoted, it is high to hardness, bearing capacity is strong, Organize the demand for the Ultra-fine Grained high-performance magnesium-alloy cup shell that relatively uniform, anisotropy is small, comprehensive mechanical property is more excellent Increasing, comprehensive performance requirement is higher and 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 exemplary embodiment, Er Qie In the case of without departing substantially from spirit or essential attributes of the invention, the present invention can be realized in other specific forms.Therefore, no matter From the point of view of which point, the present embodiments are to be considered as illustrative and not restrictive, and the scope of the present invention is by appended power Profit requirement rather than above description limit, it is intended that all by what is fallen within the meaning and scope of the equivalent requirements of the claims Variation is included within the present invention.
Moreover, it will be appreciated that although this specification is described in terms of embodiments, but not each embodiment is only wrapped Containing an independent technical solution, this description of the specification is merely for the sake of clarity, and those skilled in the art should Using specification as an entirety, the technical solutions in each embodiment can also be properly combined, forms those skilled in the art It is appreciated that 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 forming temperature and is kept the temperature, and differential-velocity extrusion shaping dies is integrally pre- It more than heat to magnesium alloy blank forming temperature and keeps the temperature;The differential-velocity extrusion shaping dies includes the superstructure with forcing press The mold component of connection, the lower die assembly and combined die being connected with forcing press substructure;The mold Component is included built in the cope plate being connected with the upper table of forcing press, the upper mold cover for seat to connect with cope plate and upper mold cover for seat Punch;The cope plate is assemblied in fastening bolt on forcing press upper table, and the upper ends of the punch are in upper mold On the inside center line of cover for seat, punch upper end is by cylinder finger setting, and surrounding is by hexagon socket head cap screw upper mold cover for seat and cope plate It is fixed, punch is made firmly to be anchored in upper mold cover for seat;The combined die includes, and "T"-shaped upper cavity die and " u "-shaped are recessed Mould, "T"-shaped upper cavity die inside are cylindrical mold cavity, and with punch clearance fit, "T"-shaped upper cavity die upper end is equipped with annular and bores End cone face /V coordinates on face, with lower die cover for seat cavity;It is revolving body cavity inside the " u "-shaped lower cavity die;"T"-shaped fovea superior Mould is mounted in the revolving body cavity of " u "-shaped lower cavity die, and the cross sectional shape that revolving body cavity and cylindrical mold cavity collectively constitute is " mountain " font extrusion chamber, extrusion chamber bottom employ " ladder " formula differential-velocity extrusion step, and so-called differential refers to "T"-shaped fovea superior " ladder " step of mould lower face has a with " ladder " step of the recessed mold cavity of the " u "-shaped of corresponding lower position in longitudinal direction Dislocation is poor, and when metal flows through this region in extrusion process, metal upper and lower surface forms differential along step-flow, flow velocity;Institute The lower die assembly stated includes lower template cover for seat, lower bolster and lower template;It is cylindrical mold cavity inside the lower die cover for seat, type Intracavitary portion and combined die clearance fit, cavity upper end is closed up with circular cone, with to upper cavity die /V load;Lower die cover for seat It is fixed on from top to bottom in lower template with lower bolster;
(4), installation mold:Mold after preheating insulation is mounted on forcing press;Finish stone is injected to combined die inner cavity Black lubricant, while finish graphitic lubricant is injected in " mountain " font extrusion chamber from top to bottom from fovea superior die tip aperture;It will Magnesium alloy blank by homogenization heat treatment is put into the upper cavity die cylindrical type intracavitary of combined die;
(5) forming process:Forcing press drives cope plate, upper mold cover for seat and the punch of mold component to move downward, and squeezes magnesium and closes Golden blank is in " mountain " font extrusion chamber along cavity flow deformation;Magnesium alloy blank is under the action of cylindrical punch pressure, warp Cross the deformation of three phases:First, by the upset deformation stage of axial similar cylinder;Second is that the radial compression large deformation stage;With Forcing press drives punch to continue to be pressed down against, and metal starts along " mountain " font extrusion chamber bottom radial compression, during this, metal Undergauge is squeezed into the smaller squeezing passage of internal diameter after flowing through differential-velocity extrusion band;Third, the corner extrusion detrusion stage;Pressure Machine drives punch to continue to be pressed down against metal into " mountain " font extrusion chamber bottom roundings region, and metal is by shear stress edge It cavity plate wall to flow axially upwards, forms the barrel of magnesium alloy cup shell;
(6) after the completion of extrusion molding:Stop moving downward for forcing press upper table;Tighten what cope plate was connected with lower die cover for seat Fastening bolt unclamps lower die cover for seat, lower bolster and the fastening bolt of lower template junction;Forcing press upper table is transported back up It is dynamic, punch is driven to rise and depart from cup shell, while cope plate drives die holder set to rise, and departs from combined die;It is logical It crosses hydraulic cylinder liftout tank to act on mandril, magnesium alloy cup shell is ejected from combined die.
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