CN106825098B - A kind of differential-velocity extrusion shaping dies of magnesium alloy high-performance cup shell - Google Patents
A kind of differential-velocity extrusion shaping dies of magnesium alloy high-performance cup shell Download PDFInfo
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- CN106825098B CN106825098B CN201710024673.4A CN201710024673A CN106825098B CN 106825098 B CN106825098 B CN 106825098B CN 201710024673 A CN201710024673 A CN 201710024673A CN 106825098 B CN106825098 B CN 106825098B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C25/00—Profiling tools for metal extruding
- B21C25/08—Dies or mandrels with section variable during extruding, e.g. for making tapered work; Controlling variation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C23/00—Extruding metal; Impact extrusion
- B21C23/02—Making uncoated products
- B21C23/18—Making uncoated products by impact extrusion
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Abstract
A kind of differential-velocity extrusion shaping dies of magnesium alloy high-performance cup shell, it is related to Metal Forming technique and 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." 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-densit structure, obtain great amount of plastic deformation, grain refining effect is notable, it is with obvious effects to the crystal grain bi-modal distribution for eliminating cup shell barrel, shorten high-performance magnesium-alloy cup shell production process.
Description
Technical field
The present invention relates to Metal Forming technique and forming technique fields, and in particular to a kind of to be squeezed for magnesium alloy materials
Pressing formation and modified differential-velocity extrusion shaping dies.
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.Cup shell is manufactured, mostly uses 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 the mechanical performance that fibre flow improves such part in profiling, has the characteristics that " 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 needs multi-pass jumping-up pulling base to reach ideal using the method for traditional backward extrusion
The tensile strength difference of refined crystalline strengthening effect, low production efficiency and formed parts anisotropy is apparent, circumferential and axial is larger.
Therefore, the research and development novel manufacturing process of magnesium alloy with high strength and ductility cups has conscientiously important meaning.
Published China Patent No. is that ZL201410820158.3 patent names are that " annular of magnesium alloy cup-shape member is logical
Road corner extrusion shaping dies and method " is a kind of novel manufacturing process preparing cup-shaped member, belongs to large plastometric set scope,
There is prodigious 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, for cup-shape member crystalline substance
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 " at
The cup shell of shape, for barrel on the face perpendicular to metal flow direction, crystal grain is in representative dual-mode state crystal grain distribution.Bimodal crystal grain
Distribution refers to that metal is crushed elongation under the action of extrusion chamber inner conical boss, and the original coarse grain in part obtains significantly thin
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 the ductile rupture that cup shell barrel sample axial tension fracture mechanism is fine grain band adjoint
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.Apparently with regard to this, " magnesium closes patent
There are certain technical limitations for the circular passage corner extrusion shaping dies and method of golden cup-shape member ".
Invention content
It is an object of the invention to provide a kind of differential-velocity extrusion shaping dies of magnesium alloy high-performance cup shell, which can come
The average equivalent strain for obtaining bigger, improves grain refining effect, significantly reduces the cupuliform of circular passage corner extrusion forming
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 high property of magnesium alloy
The differential-velocity extrusion shaping dies of energy cup shell includes under the upper mold component being connect with the superstructure of forcing press and forcing press
The lower die assembly and combined die of portion's structure connection；
The upper mold that the upper mold component includes the cope plate being connect with the upper table of forcing press, connects with cope plate
Punch built in cover for seat and upper mold cover for seat；The cope plate is assemblied in fastening bolt on forcing press upper table, described
For the upper ends of punch on the inside center line of upper mold cover for seat, punch upper end passes through interior hexagonal spiral shell by cylinder finger setting, surrounding
Bolt is fixed upper mold cover for seat with cope plate, and punch is made firmly to be anchored in upper mold cover for seat；
The combined die includes "T"-shaped upper cavity die and " u "-shaped lower cavity die, is inside the "T"-shaped upper cavity die
Cylindrical mold cavity, with punch clearance fit, "T"-shaped upper cavity die upper end is equipped with end cone face on circular cone, with lower die cover for seat cavity
Limit cooperation；It is revolving body cavity inside the " u "-shaped lower cavity die；"T"-shaped upper cavity die is mounted on the revolution of " u "-shaped lower cavity die
The cross sectional shape that build intracavitary, revolving body cavity and cylindrical mold cavity collectively constitute is " mountain " font extrusion chamber；
The lower die assembly includes lower template cover for seat, lower bolster and lower template；It is circle inside the lower die cover for seat
Cylindricality cavity, cavity inside and combined die clearance fit, cavity upper end are closed up with circular cone, to be held to upper cavity die limit
Power；Lower die cover for seat and lower bolster are fixed in lower template from top to bottom.
As a further improvement on the present invention；The lower end surface section of the "T"-shaped upper cavity die is " ladder " formula differential
Step is squeezed, corresponding lengthwise position is also provided with " ladder " formula differential-velocity extrusion platform in the mold cavity surface of " u "-shaped lower cavity die
Rank, upper and lower two " ladder " formulas differential-velocity extrusion step collectively constitute differential-velocity extrusion area.
As a further improvement on the present invention；Lower end is set there are one annular convex platform on the outside of the "T"-shaped upper cavity die, is cup
The extruding calibrating strap of shape part internal diameter, corresponding lateral position are equally provided with one section of convex annular in the recessed model cavity of " u "-shaped
Platform is the extruding calibrating strap of cup shell outer diameter, the extruding calibrating strap and the tangent connection of " u "-shaped lower cavity die cavity bottom fillet.
As a further improvement on the present invention；The "T"-shaped upper cavity die upper end is in axial direction arranged perpendicular at equal intervals
Histogram is through to " mountain " font extrusion chamber, as lubricant flow channel to hole.
As a further improvement on the present invention；The bottom of described " mountain " the font extrusion chamber, connects with differential-velocity extrusion band
Bottom surface circular passage and barrel channel are equidistant.
As a further improvement on the present invention；It is equipped in the middle part of the lower bolster and lower template and is penetrated through with combined die bottom
The push-rod hole that hole communicates, the jacking block are positioned in the inner cavity of combined die, and inner cavity clearance fit, upper surface with
" ladder " formula differential-velocity extrusion step level of " u "-shaped lower cavity die connects, and lower surface is placed on lower bolster.It opens the lower surface of jacking block
There is threaded hole, is connected through a screw thread with the mandril.
As a further improvement on the present invention；The through hole of the punch, combined die, push-rod hole, jacking block, top
Bar is located on same axis；Mode flexible back and forth runs on the through hole and mandril of combined die under more than the mandril
In through-hole.
As a further improvement on the present invention；The forcing press superstructure passes through screw and cope plate, lower die cover for seat
Connection, installs compressed spring, between lower die holder set upper side and cope plate on screw.
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, especially cavity bottom is collectively formed and uses " ladder " formula differential-velocity extrusion step.The length of step
Degree is a, a height of h, and 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
There is a dislocation 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 uses the upper and lower longitudinally displaced distance of " ladder " step for half of length of bench a/2
(passing 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, 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 also will produce torque and shear stress；In addition, " staged " radial compression step
The crush-zone constituted is that inlet calibre is big, and outlet bore is small, and metal is when being squeezed into this region also by " staged "
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 increases 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 to be significantly crushed traditional backward extrusion technology cup shell
It is organized as flat elongate strip distribution, CRYSTALLITE SIZES is made to 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 more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
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
Obtain other attached drawings according to these attached drawings.
Fig. 1 is blank mold work status diagram in extrusion molding in embodiment provided by the present invention；
Fig. 2 is blank mold work status diagram 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 forming；
Fig. 8 is the cup shell barrel position metallographic microstructure of embodiment differential-velocity extrusion provided by the present invention forming；
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- compressed springs；14- fastening bolts；15-
Vertical direction hole；16- " mountain " font extrusion chamber；17- differential-velocity extrusion steps；18- annular convex platform.
Specific implementation mode
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 specific embodiment party described herein examination is 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 includes the upper mold component being connect with the superstructure of forcing press, is connect with forcing press substructure
Lower die assembly and combined die.
- Fig. 2 is please referred to Fig.1, the upper mold component includes：The cope plate 1 that is connect 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.
Please 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, 4 upper end of "T"-shaped upper cavity die is equipped with circular cone, under
Die holder covers end cone face limit 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；Equidistant vertical direction hole 15 is in axial direction arranged in 4 upper end of "T"-shaped upper cavity die, is through to " mountain " word
Shape extrusion chamber 16, as lubricant flow channel.
Fig. 3-2 is please 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,
It is equally provided with one section of annular convex platform in 5 cavity of " u "-shaped lower cavity die, is the extruding calibrating strap of cup shell outer diameter, the extruding is fixed
Diameter 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 with circular cone with combined die clearance fit, cavity upper end inside cavity,
To limit load to "T"-shaped upper cavity die 4；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 9 or more the mandril
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, and compressed spring 13 is installed 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 30 DEG C~50 DEG C or more of Mg alloy formed 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 connect with lower die cover for seat 3, forcing press upper table sliding block (not shown) are unclamped
Rise and drives upper die component：Cope plate 1, upper mold cover for seat 2, punch 12 rise with sliding block, so that punch 12 is detached 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 the injection one in " mountain " font extrusion chamber of combined die from the lubricant aperture of 4 upper end of "T"-shaped upper cavity die
Quantitative finish graphitic lubricant；350 DEG C of magnesium alloy blanks after Homogenization Treatments are put into 4 cylinder of "T"-shaped 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 4 cylindrical cavity of "T"-shaped upper cavity die, thus in punch
Under 12 pressure, the cylindrical cavity part of Upsetting filling completely "T"-shaped upper cavity die 4, 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 connect 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 is detached 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 is detached 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, the bolt that lower template 7 is connect with lower die cover for seat 3 is twisted
Tightly.
(10) the differential-velocity extrusion forming 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, 4 intracavity diameter D of "T"-shaped 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 4 upper end of "T"-shaped upper cavity die is isometrical in an axial direction
Agent aperture.
As shown in figure 3-2, the sizing strip length L2 of "T"-shaped upper cavity die 4 is 8.8mm, the sizing belt length of " u "-shaped lower cavity die 5
Degree L1 is 24mm；Consider from metal flow is conducive to extruding force angle as big as possible is provided, 4 lower end of "T"-shaped upper cavity die
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 convex platform 18 is connect 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
Give birth to greatly shear-deformable.The inclination angle that " mountain " font shown in Fig. 3-2 squeezes the not specified all intermediate inclines of cavity wall is equal
It is 45 °.
Fig. 4-1 is please referred to, 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 be formed 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 is please referred to, the differential of 4 lower face of "T"-shaped upper cavity die squeezes
It presents a theatrical performance as the last item on a programme the differential-velocity extrusion step 17 of rank 17 and corresponding 5 intracavitary of " u "-shaped lower cavity die, wrong potential difference, dislocation are poor in a longitudinal direction
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 effect has 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 by differential-velocity extrusion step 17 shearing force；
Second is that " ladder " formula differential radial compression step is the small channel of entrance large outlet, it is golden during extruding metal
Category can be squeezed the upward extruding force effect of Step Shaft；
Third, upper and lower differential-velocity extrusion step has dislocation poor in the longitudinal direction, this dislocation it is poor during extruding metal not
But increase metal and repeatedly extrude the number of deformation up and down, and because metal contacts with Steps after, upper and lower surface is formed
Current difference makes also to be acted on by shear stress inside it to generate certain torque in metal inside.
" ladder " formula differential-velocity extrusion step 17 of the present invention, changes the stress state of metal, greatly improves 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 be in bi-modal distribution, weaken the synthesis of extrusion
Performance, and the design of " ladder " formula differential-velocity extrusion step of the present invention, have greatly been 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 is present invention extruding flow of metal.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 shear-deformable stage.With forcing press drive punch continue to
Lower extruding, metal are changed into axial flowing in fillet deformed area metal from Radial Flow, occur greatly shear-deformable.
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-densit structure 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
Ladder " formula differential radial compression area repeatedly extrudes the number of deformation, make metal in flow process repeatedly with " ladder " formula of dislocation
Reciprocation occurs for differential-velocity extrusion step, and surface is made, by more shearing forces and axial compression power, to change magnesium conjunction with internal
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 the shear-deformable area of portion's fillet
Change crystal grain to sub-micron and even nanoscale, formed high-angle boundary structure, obtain high-densit structure, magnesium alloy be greatly enhanced
The working hardening effect of material.
(3) 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 repeatedly extruded and is crushed by " ladder " formula differential-velocity extrusion step of dislocation for these deficiencies of above-mentioned technique
Coarse grain and the elongate grains being elongated effectively improve cup to which barrel radial direction crystal grain bi-modal distribution be greatly reduced
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, 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, to eliminate upset process.It directly utilizes axial compressive force, radial pressure and cuts
It is achieved with great plastic deformation to the collective effect of shearing force, contributes to break down dendritic tissue and impurity, significantly carries
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 novel differential-velocity extrusion of the present invention
Cup shell can obtain the amount of plastic deformation of bigger, have more metals to participate in the stream of 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 is 1mm/s, friction coefficient 0.25.It can visually see from analog result, the forming of circular passage corner extrusion
Cup shell average equivalent strain value (AVG) is 4.01, and the novel 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 novel differential extrusion cup shape part of the invention is noticeably greater than circular passage
Corner extrusion.To which cup shell prepared by the novel differential pressing method confirmed through the 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
Almost it is consistent, and circular passage corner extrusion is then to continuously decrease from outside to inside.This illustrate the differential-velocity extrusion of multi-ladder at
Shape method can be such that metal " is squeezed saturating " in plastic history, that is to say, that metal as much as possible can be made to be plastically deformed
The flowing of more large deformation is participated in the process.
(7) it is compared by experiment and microscopic examination, the novel 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 at
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, materials respectively barrel position perpendicular to metal flow direction face (sample bottom end face)
Microstructure observation is carried out under Zeiss metallographic microscope, Fig. 7, Fig. 8 are respectively circular passage corner extrusion forming, novel 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 novel differential extrusion forming method
Phenomenon is obviously eliminated.
(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 invention is not limited to the details of the above exemplary embodiments, 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 requires rather than above description limits, 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.
In addition, it should be understood 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
It considers the specification as a whole, the technical solutions in the various embodiments may also be suitably combined, forms those skilled in the art
The other embodiment being appreciated that.
Claims (7)
1. a kind of differential-velocity extrusion shaping dies of magnesium alloy high-performance cup shell, it is characterised in that：Include the top with forcing press
The upper mold component of structure connection, the lower die assembly and combined die being connect with forcing press substructure；Described is upper
Die assembly includes the cope plate being connect 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 limit cooperation 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
Lower end surface section for " mountain " font extrusion chamber, "T"-shaped upper cavity die is " ladder " formula differential-velocity extrusion step, corresponding vertical
To position, it is also provided with " ladder " formula differential-velocity extrusion step in the mold cavity surface of " u "-shaped lower cavity die, upper and lower two " ladder " formulas are poor
Speed squeezes step and collectively constitutes differential-velocity extrusion area, so-called differential, refer to "T"-shaped upper cavity die lower face " ladder " step with it is right
" ladder " step of the recessed mold cavity of the " u "-shaped of lower position is answered to have a dislocation poor in longitudinal direction；The lower die assembly
Including lower template cover for seat, lower bolster and lower template；It is cylindrical mold cavity, cavity inside and combined type inside the lower die cover for seat
Cavity plate clearance fit, cavity upper end are closed up with circular cone, to limit load to upper cavity die；Lower die cover for seat and lower bolster from upper and
Under be fixed in lower template.
2. a kind of differential-velocity extrusion shaping dies of magnesium alloy high-performance cup shell according to claim 1, it is characterised in that：
Lower end is set there are one annular convex platform on the outside of the "T"-shaped upper cavity die, is the extruding calibrating strap of cup shell internal diameter, corresponding
Lateral position is equally provided with one section of annular convex platform in the recessed model cavity of " u "-shaped, is the extruding calibrating strap of cup shell outer diameter, should
Squeeze calibrating strap and the tangent connection of " u "-shaped lower cavity die cavity bottom fillet.
3. a kind of differential-velocity extrusion shaping dies of magnesium alloy high-performance cup shell according to claim 1, it is characterised in that：
Equidistant vertical direction hole is in axial direction arranged in the "T"-shaped upper cavity die upper end, is through to " mountain " font extrusion chamber, makees
For lubricant flow channel.
4. a kind of differential-velocity extrusion shaping dies of magnesium alloy high-performance cup shell according to claim 1, it is characterised in that：
The bottom of described " mountain " the font extrusion chamber, the bottom surface circular passage and barrel channel to connect with differential-velocity extrusion band are equidistant.
5. a kind of differential-velocity extrusion shaping dies of magnesium alloy high-performance cup shell according to claim 1, it is characterised in that：
Further include jacking block, the push-rod hole communicated with combined die bottom through hole, institute are equipped in the middle part of the lower bolster and lower template
The jacking block stated is positioned in the inner cavity of combined die, with inner cavity clearance fit, " ladder " formula of upper surface and " u "-shaped lower cavity die
Differential-velocity extrusion step level connects, and lower surface is placed on lower bolster, and the lower surface of jacking block is provided with threaded hole, with the mandril
It is connected through a screw thread.
6. a kind of differential-velocity extrusion shaping dies of magnesium alloy high-performance cup shell according to claim 5, it is characterised in that：
Through hole, push-rod hole, jacking block, the mandril of the punch, combined die are located on same axis；It is more than the mandril
Under back and forth flexible mode run in the through hole and push-rod hole of combined die.
7. a kind of differential-velocity extrusion shaping dies of magnesium alloy high-performance cup shell according to claim 1, it is characterised in that：
The forcing press superstructure is connect by screw with cope plate, lower die cover for seat, compressed spring is installed on screw, under being located at
Between die holder set upper side and cope plate.
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| CN107442589B (en) * | 2017-09-13 | 2018-11-23 | 中北大学 | A kind of large-scale band lug magnesium alloy component shaping dies |
| CN109513762A (en) * | 2018-11-27 | 2019-03-26 | 清华大学 | It is a kind of for producing the method and die device of wide cut magnesium plate |
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