The roll spacings milling method such as helical tapered roll of large-sized aluminium alloy ultra fine grained steel bar
Technical field
The present invention relates to technical fields of mechanical processing, and in particular to the helical tapered roll of large-sized aluminium alloy ultra fine grained steel bar
Equal roll spacings milling method.
Background technology
Its equivalent strain usually should be greater than 6 when preparing nanometer materials, and traditional plastic processing method is difficult to accomplish, using super
Large plastometric set(Severe Plastic Deformation, SPD) it can realize.Modern SPD starts from Bridgemen propositions
Big pressure and shear-deformable combination forming mode, fast development starts from mid-term former Soviet Union the 1970s and western countries,
Segal has developed Equal-channel Angular Pressing technology(Equal-Channel Angular Pressing, ECAP), Valiev passes through
The change of grain structure puies forward high performance huge possibility, indicates the arrival in the microstructure epoch of SPD researchs.Nearly more than 10 year
Come, thousands of achievements in research are published.
It is universally recognized after 2006 to be defined about SPD:Block is set to generate super large strain but unobvious change block geometry
The metal forming process of the grain refining effect of high-angle boundary is presented in size, can obtain crystallite dimension in the micron-scale(100-
1000nm) and nanoscale (is less than 100nm), all can be described as a nanometer SPD(Abbreviation nanoSPD).Since nanoSPD materials have greatly
Measure the wide-angle Non-equilibrium Grain Boundary tissue containing high density dislocation and high internal stress so that material shows to be different from traditional coarse-grain material
The mechanical behavior and deformation mechanism of material.
Current existing processing technology scheme:SPD typical case's forming technique, typical SPD methods have high pressure torsion (High
Pressure Torsion, HPT), equal channel angular extrusion deformation (equal channel angular press-ing, ECAP),
Accumulate ply rolling method (Accumulative Roll Bonding, ARB), torsion squeezes(Twist Extrusion, TE)With it is multidirectional
Forging(Multi-Directional Forging, MDF).
Wherein,(1)High pressure torsion deforms:The primary sample (block or powder) being placed in support slot applies the pressure of several GPa
The characteristics of power, and two anvils above and below relative rotation make sample that intensive shear occur and deforms and crystal grain thinning, high pressure torsion is workpiece
For plate-like, size is smaller, and diameter is generally 10-20 mm, and thickness is 0.2-0.5 mm.
(2)Miter angle extruding deforming:By the cross-section channel of two intersection certain angles in mold, by material by one end
To the other end squeeze out, the change in material movement direction is allowed to by bending angle to generate pure shear shear deformation, may be repeated this at
Type process, shear strain amount increase with rolling pass.
(3)Accumulate ply rolling method:By the double-deck stacking after original plate surface treated, after heating roller welding together, then from
Centre cut off send back to surface treatment after carry out next roller welding cycle again, for ensure roll after plank can be welded together, every time
Drafts must not be less than 50%, but need strong shear stress condition in ARB process, lubricant cannot be used, this is to rolling
The service life of roller is unfavorable.
(4)Torsion squeezes:Beygelzime etc. proposes the technique.The method is also by shear-deformable crystal grain thinning
Column blank is pressed through torsion mould by forming technique, and similar with HPT, there are deformation problem of non-uniform, grain refinement effect is low
In ECAP and HPT.
(5)Multiway forging:The technique obtains large deformation by multiple orthogonal change open die forging direction.The crystalline substance of such deformation
Grain thinning effect will be significantly lower than ECAP and HPT.
Another existing processing technology scheme:Deriving method, in recent years SPD new processes emerge one after another, basic forming is former
Same above method is managed, many ECAP moldings new technologies have been derived, these methods try hard to simplify tool design, reduce energy consumption, improve
Lumber recovery, lifting workpieces size, upgrading the degree of automation etc., wherein including:
(1)ECAP deriving methods:Bending is straightened repeatedly(RCS), blank is placed between Bending Mould, is moved down with upper mold, base
Material is bent over, and becomes wavy;It is then straightened with 2 pieces of tablets, then carries out bending, by constantly repeating, changed in unobvious
Enough deformations, refiner material tissue are accumulated in the case of becoming billet size.
(2)Circulation closed die forging (CCDF), mold are vertically moved in the cavity by the lower die of some section cavity and one
Same cross-sectional punch composition.The sample of sufficient lubrication with graphitic lubricant is put into lower die, a constant temperature is heated to
Degree.Workpiece is pressed into lower die by punch, after taking-up, is rotated by 90 ° in the same direction around Z axis, lower die deformation is reinserted.This
Sample, workpiece are rotated by 90 ° between continuous channel around Z axis.In this way, it is subjected to 1,3 and 5 second compression respectively.
(3)Reciprocating extrusion(CEC), mold is made of two die cavitys, a compression strap and the punch that is positioned in two die cavitys.
Two die cavity sectional areas are equal, on same axis, pass through intermediate compression band connection.In extrusion process, sample is in punch
Under the action of, compression strap is reached, at this point, sample will be deformed by forward extrusion, punch of the workpiece after extruding in another die cavity
Under effect, Upsetting occurs.Then, another side punch is reversely pushed back workpiece by the above process, completes an extrusion cycle.
Above procedure is repeated, until obtaining desired strain.
(4)Plank continuous confined strip shearing, device using upper die and lower die and lower roll constitute two cross-sectional areas have it is a small amount of poor
Different cross one another channel.Plank is sent in die cavity, strong plastic deformation occurs in die cavity corner for plank, then from
The die cavity other side squeezes out.Feeding roller surface process groove for increase frictional force, due to before and after deformation material it is transversal
The characteristics of area remains unchanged repeatedly can carry out plank in same mold the plastic deformation of multi-pass.
(5)Ellipse spiral wait channel pressings method (ECEA), blank is under the action of extruding force, by round bar after upsetting pull
(Circle-elliptic transformation), torsion(Oval cross section reverses)With reversed upsetting pull(Ellipse-circle transformation)Process becomes round bar again.Metal
Plastic Flow, and accumulation strain are mainly generated on cross section.Circle and elliptical particularity, type is utilized in mold shape
Wedge angle region is not present in chamber, keeps metal readily flowed.Realize the combination of one-time process process various deformation pattern.
(6)Continuous angle of friction squeezes(CFAE), driven roller rotates simultaneously applies pressure P against its support element to workpiece.It is driving
Dynamic that first squeezing passage is formed between roller and workpiece support, second channel is the short slot in fixing mould component.Sheet
Workpiece is by one to eight processing, and up to 5.3, sheet material orientation remains constant for maximum equivalent logarithmic strain.
(7)A kind of HPT deriving methods are suitable for the high pressure torsion of pipe(HPTT), for pipe in rigid disk, mandrel is put into pipe
In, it is compressed under its elastic stage with compressor.It due to being compressed axially for mandrel, is radially expanded, expands by pipe and circle
The limitation of disk forms prodigious hydrostatic stress in pipe, and larger frictional force is generated in the both sides of pipe.Keeping mandrel fixed
In the case of, the deformation of pipe is realized by external torque rotating disk.In twist process, deformation pattern is partial cut, shear surface
Normal direction is the radial direction of pipe, and shear direction is parallel to circumferencial direction.
(8)A kind of TE deriving methods, superelevation torsion(STS), make the region than other two by local heating and cooling
Part deformation resistance, makes torsional strain(TS)Region localizes.While generating the areas TS, bar is moved along longitudinal axis,
Therefore super large plastic strain is continuously generated on entire bar.This new process STS includes the other parts generation office relative to bar
The bar of the movement of portion's soft zone and region along longitudinal direction.An important feature of STS is that the cross sectional dimensions of bar is kept in strain
It is constant.
Aluminum alloy materials have more excellent characteristic than other non-ferrous metals, steel, plastics and timber etc., if density is small,
About 2.7g/cm3, almost it is the 1/3 of copper or steel;Preferable corrosion resistance;Good electrical and thermal conductivity performance;Forming easy to process
(Plasticity good toughness);Good mechanical property etc..It is relatively fewer for the patent report of aluminium alloy Ultra-fine Grained technique both at home and abroad.It breathes out
Your shore polytechnical university Zhang Kai's cutting edge of a knife or a sword et al. is in patent【CN 101857925 A】It is referred to a kind of preparation side of ultrafine grained Ni-Al alloy
Method, wherein referring to the technological parameters such as preparation and heating temperature, heating rate, the application load of nickel alumin(i)um alloy powder.Although passing through
The average grain size that the technique obtains is 400nm, but in process program ball mill frequency of use is excessive and usage time mistake
It is long, and cause ultrafine grained Ni-Al alloy constant and finished size to be restricted using 1300 DEG C of high temperature furnaces, it is difficult to realization amount
Production.Jiangsu University Liu expires equality people in patent【CN105331858 A】In be referred to using Equal-channel Angular Pressing method prepare
The method of Ultra-fine Grained high-strength/tenacity aluminum alloy, although the background introduction of the method this patent is, it has been proposed that the corner by multi-pass squeezes
Pressure and solution treatment obtain 190 ~ 260nm Ultra-fine Graineds, but finished size is smaller, be 20 × 20 × 100mm ~ 100 × 100 ×
350mm, it is difficult to meet technical grade demand.Liu Chongyu of Guilin University of Technology etc. is in patent【CN107058829 A】In be referred to
A kind of preparation method of super fine crystal material.The method mainly makes to generate Ultra-fine Grained in the aluminium alloy of element containing scandium.Although what is obtained is flat
Equal crystallite dimension is 500nm, but the maximum tensile strength of the alloy only reaches 390 ~ 460MPa, is closed with other trade mark Ultra-fine Grained aluminium
There is also larger gaps for the tensile strength of gold.Central South University Xiao is for red et al. in patent【CN101876041 A】It is referred to one kind
The preparation method of the ultra-fine heat-resisting aluminium alloy of Al-Cu-Mg-Ag systems.The preparation method of this patent be first with extrusion ratio be 8 ~ 15 into
Then row hot extrusion carries out the isometrical angle hot extrusion of multi-pass at 350 ~ 430 DEG C, obtained crystallite dimension is in 600nm ~ 2000nm models
In enclosing, but extrusion ratio be 8 ~ 15 extrusion process and multi-pass Equal Channel Angular Pressing to mould strength, die wear and product size
Etc. limitation it is larger, it is difficult to carry out volume production in the industrial production.And the degree of refinement of aluminium alloy crystal grain is relatively low in the patent.
For the paper of aluminium alloy Ultra-fine Grained technique report, Equal Channel Angular Pressing is used mostly, the modes such as ball milling heating extruding are to aluminium
Alloy is deformed, but involved alloy size is smaller, it is difficult to generate industrialized application value.
Known to comprehensive analysis:The aluminium alloy fine grain technique referred in existing patent or paper mostly uses aluminium alloy cast ingot
Ball milling repeatedly, the technique that then method of hot extrusion or use multi-pass hot extrusion and Equal Channel Angular Pressing combine.But these are specially
The ultra-fine grained aluminium alloy geometric dimension obtained in profit is smaller, can not temporarily be generalized to aerospace field.
Invention content
The purpose of the present invention is to provide the isometric helix milling methods of large-sized aluminium alloy ultra fine grained steel bar, in solution
State the problems such as deformed area proposed in background technology is smaller, penetrability is poor, and size and degree of refinement are limited, efficiency is low.
The roll spacings milling methods such as the helical tapered roll of large-sized aluminium alloy ultra fine grained steel bar of the present invention, include the following steps:
S1:It is 40-200mm to choose diameter dimension D, and length is the aluminum alloy blank of 300-5000mm;
S2:Above-mentioned aluminum alloy blank is placed in heating furnace and is heated to 380-450 DEG C, heating time is:Aluminium alloy alloy blank
Diameter D ×(0.6~0.8)min;
S3:Aluminum alloy blank after heating is transported to from heating furnace in skew rolling mill deflector chute, transhipment time 5-20s;
S4:Feeding is carried out in the deflector chute of skew rolling mill, and aluminum alloy blank is sent into the deformation between skew rolling mill entrance and exit
Area, aluminum alloy blank, which is moved in deformed area inside spin until deforming, to be terminated, and obtains the rods and bars of aluminium alloy of a diameter of Dm, wherein m is
Roll number;
S5:Above-mentioned S2-S4 steps are repeated, carrying out 2-14 screw rolling to aluminum alloy blank obtains aluminium alloy integrally ultra-fine crystal bar
Material;
The skew rolling mill is two-roller skew-rolling machine, and the roll is single cone-shaped roll, and helical groove is provided on the roll, and
The precession direction of helical groove is identical as the precession direction in the aluminum alloy blank operation of rolling, and cone angle gamma 1 is 15-17 degree, and is rolled
The arc radius r that roller bites aluminum alloy blank is 40-300mm, and roll feed angle α is 13-15 degree, and the roll off angle beta of roll is 15-
17 degree, the 89%-99% that the roll space D g between two rolls is aluminum alloy blank diameter D, roll rotational speed n are 25-40r/
min;
The aluminum alloy blank is 2219 rods and bars of aluminium alloy of large scale;
In the S5 steps, the heating time for repeating the operation of rolling is:Rods and bars of aluminium alloy diameter Dm ×(0.3~0.4)min.
Preferably, roll small end face is set as arc surface, and circular arc radius surface is 40-300mm.
Preferably, Groove Ovality Factor is guide plate away from DdThe ratio between with roll spacing Dg, aluminum alloy blank is deforming in S4 steps
Groove Ovality Factor is used to be rolled for 1.28-1.45 in area.
Preferably, in the aluminum alloy blank operation of rolling, the roll spacing Dg between two rolls immobilizes, and is advantageously implemented
Multi-pass repeats to roll.
Preferably, the screw pitch ι of helical groove is 10 ~ 30mm, and the high h of tooth is 10 ~ 30mm.
Preferably, in S5 steps repeat the operation of rolling, deformed area shape remains unchanged.
Compared with prior art, the beneficial effects of the invention are as follows:
(1)Deformed area is worn deeply greatly, and large scale entirety ultrafine-grained (UFG) microstructure can be obtained.Plastic deformation inside oblique milling process in which materials
Consist of two parts, first, the compressive deformation between roll, this is deformed into periodic breaks deformation, and another part is to continue to occur
Torsional deflection.The superposition of compression and torsional deflection makes during oblique milling that generation is clearly distinguishable from the three-dimensional routinely forged in deformed area
Severe plastic deformation;(2)Diameter of rod, which remains unchanged, before and after oblique milling reciprocally carries out multi- pass rolling.Oblique milling process exists wide
It opens up, the equivalent diameter in aluminum alloy blank cross section remains unchanged;(3)Continuous-stable local deformation, rolling loads are small, deform
Cheng Pingwen.The real contact area of workpiece and aluminum alloy blank is only the very little one of aluminum alloy blank surface area during oblique milling
Point, it is deformed for localized contact, thus load is small;(4)Pressure-torsion complex three-dimensional drastic deformation, can obtain ideal crystal grain refinement
Effect.
Description of the drawings
Fig. 1 is roll schematic diagram of the present invention.
Fig. 2 is original structure β crystal grain schematic diagrames.
Fig. 3 is that the rolling number of the embodiment of the present invention one is 2 schematic diagrames.
Fig. 4 is that the rolling number of the embodiment of the present invention one is 6 schematic diagrames.
Fig. 5 is each mold relative position of oblique milling process of the present invention.
Fig. 6 is each mold relative position vertical view of oblique milling process of the present invention.
Fig. 7 is that oblique milling of the present invention passes through each mold relative position left view of journey.
Fig. 8 is oblique milling process of the present invention deformed area schematic diagram.
Reference numeral:1- rolls, 2- aluminum alloy blanks, 3- guide plates.
Specific implementation mode
The roll spacings milling methods such as the helical tapered roll of large-sized aluminium alloy ultra fine grained steel bar of the present invention, include the following steps:
S1:It is 40-200mm to choose diameter dimension D, and length is the aluminum alloy blank 2 of 300-5000mm;
S2:Above-mentioned aluminum alloy blank 2 is placed in heating furnace and is heated to 380-450 DEG C, heating time is:Aluminium alloy alloy blank
Diameter D ×(0.6~0.8)min;
S3:Aluminum alloy blank 2 after heating is transported to from heating furnace in skew rolling mill deflector chute, transhipment time 5-20s;
S4:Feeding is carried out in the deflector chute of skew rolling mill, and aluminum alloy blank 2 is sent into the deformation between skew rolling mill entrance and exit
Area, aluminum alloy blank 2, which is moved in deformed area inside spin until deforming, to be terminated, and obtains the rods and bars of aluminium alloy of a diameter of Dm, wherein m is
Number is rolled, a diameter of D1 of the rods and bars of aluminium alloy once obtained is rolled, rolls a diameter of of the rods and bars of aluminium alloy obtained twice
D2, and so on;
S5:Above-mentioned S2-S4 steps are repeated, carrying out 2-14 screw rolling to aluminum alloy blank 2 obtains aluminium alloy entirety Ultra-fine Grained
Bar;
The skew rolling mill is two-roller skew-rolling machine, and the roll 1 is single cone-shaped roll 1, and helical groove is provided on roll 1, and
The precession direction of helical groove is identical as the precession direction in 2 operation of rolling of aluminum alloy blank, and cone angle gamma 1 is 15-17 degree, and is rolled
The arc radius r that roller 1 bites aluminum alloy blank 2 is 40-300mm, and 1 feed angle α of roll is 13-15 degree, the roll off angle beta of roll 1
For 15-17 degree, the 89%-99% that the 1 space D g of roll between two rolls 1 is 2 diameter D of aluminum alloy blank, 1 rotating speed n of roll are
25-40r/min;
The aluminum alloy blank 2 is 2219 rods and bars of aluminium alloy of large scale;
In the S5 steps, the heating time for repeating the operation of rolling is:Rods and bars of aluminium alloy diameter Dm ×(0.3~0.4)min.
1 small end face of roll is set as arc surface, and circular arc radius surface is 40-300mm.
Groove Ovality Factor is guide plate 3 away from DdThe ratio between with roll spacing Dg, aluminum alloy blank 2 is adopted in deformed area in S4 steps
It is that 1.28-1.45 is rolled with Groove Ovality Factor.
In 2 operation of rolling of aluminum alloy blank, the roll spacing Dg between two rolls 1 immobilizes, and is advantageously implemented multiple tracks
It is secondary to repeat to roll.
The screw pitch ι of helical groove is 10 ~ 30mm, and the high h of tooth is 10 ~ 30mm.
In S5 steps repeat the operation of rolling, deformed area shape remains unchanged.
This patent is existed using tapered roll equal roll spacings rolling to rods and bars of aluminium alloy carries out, the advantage of such whole Ultra-fine Grained technique
In by 1 size Control of roll, roll 1 is longer for deformed area, and deformed area size is bigger, and is rolled by the helical on the tapered roll
The power-assisted of slot deforms, and on the basis of original deformation, then is superimposed small-scale compression and is bent shear-deformable, final realization super large modeling
Property deformation, have the function that crystal grain thinning.Secondly deformation process is sent into for spiral, therefore there are axial, radial and circumferential three
To effects of strain, deformed area penetrates with the obvious advantage.After aluminum alloy blank 2 is drawn into roll 1, cross section becomes ellipse,
During being threadingly advanced, since transverse radius is more than 1 spacing of roll, aluminum alloy blank 2 bears always the small deformation of roll 1
Amount compression, the rotation of deformed area arbitrary point are turned around, twice by the compression of roll 1;Can repeated multiple times realization screw rolling, due to large hole
Type ellipse coefficient, the diameter of rod after screw rolling are more than roll spacing, and deformed rolled piece can be repeated multiple times in same deformation
Under Parameter Conditions, by repeat-rolling, the deflection of bigger can be obtained in this way;Using larger feeding angle and big roll off angle, can obtain
What must more be stablized is threadingly advanced power, to adapt to the demand of large plastometric set, can produce diameter dimension in 40-200mm, length
Spend 2219 aluminium alloy entirety ultra fine grained steel bars of the size within the scope of 300 ~ 5000mm.Therefore this patent is that large-sized aluminium alloy is whole
The industrialized production of body ultra fine grained steel bar provides the selection of an actuality.
The type of material processing is generally distinguished with recrystallization temperature, more than recrystallization temperature is hot-working, recrystallization temperature
It is below cold working, prior art preparation Ultra-fine Grained is all made of cold working, since deflection is inadequate, can only be obtained so that dislocation is accumulative
Smaller crystal grain, but this crystal grain thermal stability is poor, cannot be heat-treated.The purpose of this patent is to obtain to be heat-treated
Crystal grain, i.e., Ultra-fine Grained is obtained by way of accumulating large deformation by recrystallization, to be different from traditional cold working difference
It opens.
Embodiment one:
Using above-mentioned technical parameter, design processing screw rolling roll 1 is as shown in Figure 1;
S1:2219 aluminium alloy of primary deformable parameters selection aluminium alloy, a diameter of 100mm, length 800mm;Spiral roll 1 is stung
It is 60mm to enter arc radius r, and tapered roll cone angle gamma 1 is 16 °, and 13 ° of feed angle, roll off angle is 16 °, and 1 screw pitch of spiral roll is
13mm, the high h of tooth are 11mm, and 1 space D g of roll is the 90% of blank diameter D, Groove Ovality Factor 1.28, and 1 rotating speed of roll is
32r/min;
S2:380 DEG C of aluminium alloy cylindrical blank is heated in heating furnace, heating time is 70 minutes;
S3:The blank that would be heated to temperature is transported to from heating furnace in punch deflector chute, transhipment time 10s;
S4:Blank, which is moved in deformed area inside spin until deforming, to be terminated.
S5:Repeat-rolling 2 times and the analysis of 6 sub-samplings, notable for the effect of aluminum grain refinement, crystallite dimension is thin
It is small, and repeatedly the heating time of the operation of rolling is:Rods and bars of aluminium alloy diameter Dm ×(0.3~0.4)Min, wherein m are rolling number,
A diameter of D1 of the rods and bars of aluminium alloy once obtained is rolled, rolling is to use the rods and bars of aluminium alloy of a diameter of D1 as base twice
Material is rolled again, a diameter of D2 of obtained rods and bars of aluminium alloy, and so on, in S5 steps repeat the operation of rolling, become
Shape area shape remains unchanged.
Based on examples detailed above, original structure is as shown in Fig. 2, average grain size is 70um or so;It uses present invention side
Method, Fig. 3 are to roll the crystal grain figure that number is 2, and wherein crystallite dimension is 10um or so, degree of grain refinement 85.7%;Fig. 3 is
The crystal grain figure that number is 6 is rolled, wherein crystallite dimension is 3um or so, degree of grain refinement 95.7%.Its operation principle such as Fig. 8
Shown, the position relationship between roll 1 and guide plate 3 is as shown in Fig. 5, Fig. 6 and Fig. 7.
In summary:Provided by the present invention for the whole ultrafine grain preparation method thereof of rods and bars of aluminium alloy, pass through design spiral
The shape of tapered roll, and keep roll spacing in deformed area constant, multiple tracks repeatedly is carried out using super large deformed area Groove Ovality Factor
Secondary rolling is gradually accumulated as super large plastic deformation;Moreover, this method can multi-pass carry out screw rolling, for variety classes aluminium
Alloy, rolling number is within the scope of 2-14, and best for the effect of aluminum grain refinement, the whole Ultra-fine Grained size obtained is most
It is small.The technique is suitable for the continuous severe plastic deformation of rods and bars of aluminium alloy low load of various sizes specification and type.It is used to prepare
The integral fine crystal or ultra fine grained steel bar of 1000 ~ 3000nm.And existing severe plastic deformation rigid resistance can be overcome big, it can only process
The deficiency of small size workpiece.
The foregoing is only a preferred embodiment of the present invention, but scope of protection of the present invention is not limited thereto,
Any one skilled in the art in the technical scope disclosed by the present invention, according to the technique and scheme of the present invention and its
Inventive concept is subject to equivalent substitution or change, should be covered by the protection scope of the present invention.