CN109772891B - Reverse-cone spiral roller superfine crystal rolling method for large-size aluminum alloy bar - Google Patents
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Abstract
The invention discloses a method for rolling ultrafine crystals of a reverse conical helical roller of a large-size aluminum alloy bar, relates to the field of machining, and particularly relates to a method for rolling ultrafine crystals of a reverse conical helical roller of a large-size aluminum alloy bar, which comprises the following steps: the design of a rolling tool specifically comprises the design of a roller and the design of a guide plate, wherein the roller is a hyperbolic surface type circular truncated cone-shaped spiral roller; constructing a deformation zone: the curved surfaces of the two guide plates are oppositely arranged, the two rollers are arranged between the guide plates, and the area enclosed by the two guide plates and the two rollers is a deformation area; constructing an equiovality deformation zone: the ovality in the deformation zone is kept unchanged; selecting a rolling feeding mode: a reverse rolling mode; the invention relates to a reverse-cone helical roller superfine grain rolling method for large-size aluminum alloy bars, which can generate severe plastic deformation on the premise of obviously inhibiting the central Mannesian effect by designing a hyperbolic surface type truncated cone-shaped helical roller and a curved surface-shaped guide plate and constructing an equal-ellipticity deformation zone.
Description
Technical Field
The invention relates to the field of machining, in particular to a method for rolling ultrafine crystals of a reverse-cone spiral roller of a large-size aluminum alloy bar.
Background
The ultra-fine grain/nano-grain material and the preparation technology are one of the research hotspots in the field of the current material science. Research in this direction has focused on efforts to continuously increase the level of toughness in polycrystalline materials by continuing grain refinement. Among them, the research results of the technique of Severe Plastic Deformation (SPD) have been particularly noticed.
Currently, the mainstream SPD process includes five methods of High Pressure Torsion (HPT), equal channel angular Extrusion (ECAP), cumulative pack rolling (ARB), Multidirectional Forging (MF), and Torsional Extrusion (TE), wherein:
(1) high-pressure torsional deformation: the plastic processing forming process is characterized in that a workpiece is disc-shaped, the size is small, the diameter is generally 10-20mm, and the thickness is 0.2-0.5 mm.
(2) Equal channel angular extrusion deformation: the sample passes through the corners of two same channels under the pressure action of the punch to generate large shearing plastic deformation, and the shape and the area of the cross section of the sample are kept unchanged, so that the strain of each pass can be accumulated through repeated extrusion.
(3) Cumulative pack rolling method: the method comprises the following steps of carrying out surface degreasing steel brush treatment on a plate material to expose a fresh surface of the plate material, then overlapping the two plate materials together, rolling at room temperature or a certain heating temperature to enable the two plate materials to be combined into one plate material, cutting off the rolled and combined plate material from the middle to obtain two composite plates with the same size as an original single plate material, and then carrying out a new round of processing on the two obtained composite plate materials.
(4) Torsion extrusion: beygelzime et al teach this process. The method also adopts a forming technology of thinning crystal grains through shearing deformation, and the columnar blank is extruded through a torsion die, so that the method has the similar problem of uneven deformation as HPT, and the effect of thinning the crystal grains is lower than that of ECAP and HPT.
(5) Multidirectional forging: repeated upsetting and drawing-out are carried out on the material in different directions, and large plastic deformation is introduced, so that grain refinement and material performance improvement are realized. However, the method has obvious strain gradient, the strain uniformity is poorer than that of other SPD methods, and the size of the actual effective severe deformation region can not meet the requirement of industrial grade. The grain refining effect is thus significantly lower than that of ECAP and HPT.
(6) A constant roll spacing rolling method (application No. 201810172516.2) of a spiral conical roll of a large-size aluminum alloy ultrafine-grained bar adopts a positive conical roll to roll a round blank at a constant roll spacing, and the technical parameters in the forming process include that a feeding angle α is 13-15 degrees, a rolling angle β is 15-17 degrees, the rotating speed n of the roll is 25-40r/min, the diameter reduction rate epsilon is 1-11%, the pass ovality is 1.28-1.45, the thread pitch is 10-30 mm, the tooth height is 10-30 mm and the like, so that the preparation of the large-size ultrafine-grained bar is realized.
The aluminum alloy is a non-ferrous metal structural material which is most widely applied in industry, and the density is close to 2.7g/cm3About1/3, which is copper, has good electrical and thermal conductivity and high strength, and has been widely used in the aerospace, automotive, mechanical manufacturing, marine and chemical industries. A high-strength and high-toughness ultrafine grain wrought aluminum alloy and a preparation method thereof are provided in a patent (CN 105401018A) of Li political resources of Kaiyi novel materials Co. The purposes of refining crystal grains and improving mechanical properties are achieved by methods of smelting, solution heat treatment and forging, and due to the fact that the requirement of the casting process is strict, the casting is prone to defects and difficult to meet the industrial requirement.
The patent of Liu Chong Yu et al of Guilin science and engineering university (CN 107058829A) mentions a preparation method of an ultrafine crystal material. The method mainly generates superfine crystals in the scandium-containing aluminum alloy. Although the average grain size is 500nm, the maximum tensile strength of the alloy only reaches 390-460 MPa, and the maximum tensile strength is greatly different from the tensile strength of other grades of ultrafine grained aluminum alloy.
The patent [ CN 108359820A ] by the Chengqiao et al of the institute of materials of the Chinese institute of engineering and physics refers to a preparation method of ultrafine-grained beryllium-aluminum alloy and its products. The pre-alloying realizes the mixing and dissolving of alloy components, and the rapid cooling of the melt is realized under the condition of small superheat degree, and finally the novel ultrafine crystal beryllium-aluminum alloy with fine and compact crystal grains and uniform-sized isometric crystal microstructure is obtained. But the finished product has smaller size and is difficult to meet the industrial requirement.
The patent (CN 108588517A) of Wanming Jun of combined-fertilizer remote new material science and technology Limited company refers to an ultra-fine grained aluminum alloy applied to pipe fitting preparation. The aluminum alloy is deformed by ball milling and heating, and is limited by the size, so that the industrial application value is difficult to generate.
The prior art has the following disadvantages:
(1) in the ECAP deformation process, the blank is in full contact with the die, the friction force is large, so the forming load is large, the size of a finished product is small, the material utilization rate is low, the production efficiency is low, and the preparation of the large-size ultrafine crystal material which meets the industrial requirement is difficult to realize.
(2) The HPT forming load is huge, the existing forming equipment generally does not have the loading capacity of more than dozens of GPa of an industrial large-size product, and is only suitable for forming an ultrathin product such as a film, and the blank is a cylinder with phi 10-15 × 1-10 mm before deformation.
(3) ARB processes are limited by the volume of the deformation zone and the uniformity of the deformation, with the thickness of the deformation zone being only of the order of mm. Meanwhile, the prepared ultrafine crystals are cake-shaped elongated crystal grains, and the mechanical property of the ultrafine crystals is poorer than that of three-dimensional equiaxial crystal grains. Therefore, ARB can only produce ultra-thin sheets, limited by the loading capacity and the degree of deformation non-uniformity.
(4) Due to serious deformation nonuniformity, the MF and TE have uneven grain size, poorer grain structure stability and reduced performance, and large-size forgings cannot be prepared.
(5) The method for rolling the large-size aluminum alloy ultra-fine crystal bar by the constant roll spacing of the spiral conical roll (application No. 201810172516.2) has the following problems: 1) the shape of the roller in the prior art is a single-cone roller, and after a blank enters the roller, the speed of the contact area between the roller and the blank is gradually increased due to the gradual increase of the diameter of the roller, so that the deformation speed difference of the center and the edge of the blank is increased, and the deformation unevenness is aggravated.
2) The roller spacing is equal, the thread pitch iota and the tooth height h of the spiral groove are constant values, and the range is 6-15 mm. The diameter reduction rate is gradually reduced, and the deformation is smaller, so that the grain refining effect is gradually weakened.
The comprehensive analysis shows that: the aluminum alloy ultrafine grain process mentioned in the existing patent or paper is limited by the volume of a deformation area, only small-size ultrafine grain materials can be prepared, and large-size (phi 60-phi 500 mm) materials of industrial-grade integral ultrafine grains are difficult to prepare.
Disclosure of Invention
The invention aims to provide a reverse-cone spiral roller superfine crystal rolling method for large-size aluminum alloy bars, which can obviously reduce transverse widening deformation, reduce the tensile stress of the core, increase the thread pitch, and reduce the repeated rolling times of spiral rolling, thereby inhibiting the Mannich effect, reducing the probability of crack occurrence, improving the deformation uniformity, gradually enhancing the grain refining effect and having better grain refining effect.
The invention relates to a reverse-cone spiral roller superfine crystal rolling method of a large-size aluminum alloy bar, which comprises the following steps of:
1) the design of rolling tool specifically includes roll design and baffle design, sets up the roll into hyperbolic face class round platform shape spiral roller, specifically is: the generatrix of the roller is formed by connecting a tooth-shaped outer contour curve and a section of smooth curve; setting one surface of the guide plate as a curved surface;
2) constructing a deformation zone: the curved surfaces of the two guide plates are oppositely arranged, the two rollers are arranged between the guide plates, and the area enclosed by the two guide plates and the two rollers is a deformation area;
the direction from the center of the large end face of the roller to the center of the small end face of the roller on one of the two rollers is a first direction; the direction from the center of the large end surface of the roller to the center of the small end surface of the roller on the other roller is a second direction;
an included angle between the first direction and the second direction is an acute angle;
3) constructing an equiovality deformation zone: the ovality in the deformation zone is kept unchanged;
4) selecting a rolling feeding mode: the reverse rolling mode is that the blank enters a deformation zone from the large end of a roller in the rolling process;
5) selecting materials: selecting 2219 aluminum alloy blanks with the diameter of 60-500mm and the length of 300-15000 mm;
6) rolling: the two rollers respectively rotate around the central axes thereof, after the blank is heated, the heated blank is sent into the deformation zone according to the rolling feeding mode, the blank spirally advances in the deformation zone and is output from the small ends of the rollers, the variable cross-section rolling is realized, and after the rolling process is finished, the blank is cooled.
Preferably, the curve connecting the tooth-shaped top ends of the rollers is a first curve, a connecting line between two ends of the first curve is a first central line, a curve close to the small end on the roller generatrix is a second curve, and a connecting line between two ends of the second curve is a second central line;
the maximum distance between a point on the first curve and the first middle line is not more than 10mm, and the maximum distance between a point on the second curve and the second middle line is not more than 5 mm;
an included angle between the first central line and the second central line is 4-7 degrees.
Preferably, the area of the deformation area corresponding to the curved surface formed by the curve of the toothed outer contour on the roller rotating around the roller axis is a rolling area, the pitch of the inner thread in the rolling area is decreased progressively, and the area of the deformation area corresponding to the curved surface formed by the second curve on the roller rotating around the roller axis is a rounding area; the length of the rolling area is 2.5-5 times of the length of the rounding area.
Preferably, the diameter of the large end of the roller is 3-6 times of the diameter of the blank, and the diameter of the small end of the roller is 2.5-4 times of the diameter of the blank.
Preferably, the ovality is the ratio of the maximum distance between the two guide plates and the distance between the two rolls in the same cross section of the deformation zone, the ovality is equal at any cross section of the deformation zone, and the ovality is 1.05-1.07.
Preferably, the blank is heated in a heating furnace at 390-470 ℃ for T = Db× (0.6-0.8) min, wherein D isbIs the diameter of the blank in mm;
the taper angle inclination α of the roll surface in the deformation zone is 3.5-4.5 degrees, the taper angle inclination α of the roll surface is an included angle between a first central line and a rolling line, the feed angle β is 21.5-23.5 degrees, the feed angle is an included angle of the projection of the axis of the roll and the rolling line on a horizontal plane containing the rolling line in the rolling process, the rolling angle gamma is 18.5-20.5 degrees, the rolling angle gamma is an included angle of the projection of the axis of the roll and the rolling line on a vertical plane containing the rolling line in the rolling process, the rotating speed n of the roll is 40-68R/min, the diameter reduction rate epsilon is 45-62%, the diameter reduction rate epsilon is the ratio of the difference between the diameter of a blank and the diameter of a rolled bar to the diameter of the blank, the profile parameters of the tooth profile are that the pitch P is 14-23mm and the radius R of the tooth profile is 6-9 mm;
and the blank cooling is blank air cooling or blank water cooling to room temperature.
The invention has the following beneficial effects:
(1) the invention relates to a reverse-cone helical roller superfine grain rolling method for large-size aluminum alloy bars, which can generate severe plastic deformation on the premise of obviously inhibiting the central Mannesian effect by designing a hyperbolic surface type truncated cone-shaped helical roller and a curved surface-shaped guide plate and constructing an equal-ellipticity deformation zone.
(2) By reasonably designing special deformation tools and technical parameters of a feeding angle, a rolling angle, a roller rotating speed and an ovality, the transverse spreading deformation can be obviously reduced, the core tensile stress is reduced, the thread pitch can be increased, the repeated rolling times of spiral rolling are reduced, the Mannich effect is inhibited, the occurrence probability of cracks is reduced, and the deformation uniformity is improved.
(3) The preparation method is reverse rolling, the roller is a hyperbolic surface type circular truncated cone-shaped spiral roller, the blank enters a rolling deformation area from the end with the largest diameter of the roller, and plastic deformation occurs after the blank is bitten; after the blank enters a rolling deformation area between the rollers, the component speed of the rollers along the advancing direction of the rolled piece is gradually reduced along with the reduction of the diameter of the rollers in the contact rolling deformation area, the advancing of the rolled piece is blocked, and the deformation unevenness of metal along the axial direction is reduced, so that the deformation uniformity is improved.
(4) The included angle between the first central line and the second central line, namely the hyperboloid included angle theta of the roller is 4-7 degrees, the ratio of the length of a rolling area to the length of a rounding area can be effectively controlled, the surface quality and the deformation uniformity of a rolled workpiece are improved, the rolling area is in a single cone shape with the roller distance being sharply reduced, the taper angle inclination α of the roller surface is 3.5-4.5 degrees and is 1.2-2.5 times of that of conventional Mandarin type inclined rolling, the diameter compression deformation in doubled unit time can be realized, the deformation degree can always keep large plastic deformation, namely the grain refining effect can be gradually enhanced, and the grain refining effect is better.
(5) The spiral curved surface roller is adopted for rolling, so that the flow speed difference between the surface layer and the core metal of the blank can be obviously inhibited, the radial uneven deformation degree is reduced, and the generation of tensile stress is inhibited. Meanwhile, the repeated twisting and folding action among the spiral lines can double the grain refining effect.
Drawings
Fig. 1 is a schematic view of a hyperbolic truncated cone-like spiral roller.
FIG. 2 is a schematic view of a double-curved truncated cone-like spiral roller used in one embodiment.
Fig. 3 is a front view of the rolling process.
Fig. 4 is a schematic sectional view taken along line a-a in fig. 3.
Fig. 5 is a top view of the rolling process.
Fig. 6 is a diagram of the initial microstructure of 2219 aluminum alloy.
FIG. 7 is a microstructure of 2219 aluminum alloy after rolling in the first example.
Reference numerals: 1-roller, 2-guide plate and 3-blank.
Detailed Description
The invention relates to a reverse-cone spiral roller superfine crystal rolling method of a large-size aluminum alloy bar, which comprises the following steps of:
1) the design of rolling tool specifically includes 1 design of roll and 2 designs of baffle, sets up roll 1 into hyperbolic face class round platform shape spiral line roller, specifically is: the generatrix of the roller 1 is formed by connecting a tooth-shaped outer contour curve and a section of smooth curve; one surface of the guide plate 2 is set to be a curved surface;
2) constructing a deformation zone: the curved surfaces of the two guide plates 2 are oppositely placed, the two rollers 1 are placed between the guide plates 2, and the area enclosed by the two guide plates 2 and the two rollers 1 is a deformation area;
3) constructing an equiovality deformation zone: the ovality in the deformation zone is kept unchanged;
4) selecting a rolling feeding mode: the reverse rolling mode is that the blank 3 enters a deformation zone from the large end of the roller 1 in the rolling process;
5) selecting materials: selecting 2219 aluminum alloy blank 3 with the diameter of 60-500mm and the length of 300-15000 mm;
6) rolling: the two rollers 1 respectively rotate around the central axes thereof, after the blank 3 is heated, the heated blank 3 is sent into a deformation zone according to the rolling feeding mode, the blank 3 spirally advances in the deformation zone and is output from the small ends of the rollers 1, the variable cross-section rolling is realized, and after the rolling process is finished, the blank 3 is cooled.
The curve connected with the top end of the tooth shape of the roller 1 is a first curve, the connecting line between the two ends of the first curve is a first central line, the curve on the bus of the roller 1 close to the small end is a second curve, and the connecting line between the two ends of the second curve is a second central line;
the maximum distance between a point on the first curve and the first middle line is not more than 10mm, and the maximum distance between a point on the second curve and the second middle line is not more than 5 mm;
an included angle between the first central line and the second central line is 4-7 degrees.
The area of the deformation area corresponding to the curved surface formed by the tooth-shaped outer contour curve of the roller 1 rotating around the axis of the roller 1 is a rolling area, the distance between the inner threads of the rolling area is decreased progressively, and the area of the deformation area corresponding to the curved surface formed by the second curve of the roller 1 rotating around the axis of the roller 1 is a rounding area; the length of the rolling area is 2.5-5 times of the length of the rounding area.
The diameter of the large end of the roller 1 is 3-6 times of the diameter of the blank 3, and the diameter of the small end of the roller 1 is 2.5-4 times of the diameter of the blank 3.
The ovality is the ratio of the maximum distance between the two guide plates 2 and the distance between the two rollers 1 in the same cross section of the deformation area, the ovality at any cross section in the deformation area is equal, and the ovality is 1.05-1.07.
Heating the blank 3 by heating the blank 3 in a heating furnace at 390-470 ℃, wherein the heating time T is T = Db× (0.6-0.8) min, wherein D isbIs the diameter of the blank 3, and the unit is mm;
the taper angle α of the roll surface in the deformation zone is 3.5-4.5 degrees, the feed angle β is 21.5-23.5 degrees, the rolling angle gamma is 18.5-20.5 degrees, the rotating speed n of the roll 1 is 40-68R/min, the diameter reduction rate epsilon is 45-62%, the tooth profile outer contour parameters are that the screw pitch P is 14-23mm, and the tooth profile radius R is 6-9 mm;
and cooling the blank 3 to be the air cooling of the blank 3 or the water cooling of the blank 3 to the room temperature.
The first embodiment is as follows:
the following example illustrates a 2219 aluminum alloy bar with a specification of phi 94 × 400 of a blank 3, however, the invention is not limited thereto, and 2219 aluminum alloy bars of other specifications can be produced by the method of the invention.
1) The design of rolling tool specifically includes 1 design of roll and 2 designs of baffle, sets up roll 1 into hyperbolic face class round platform shape spiral line roller, specifically is: as shown in fig. 2, a generatrix of the roller 1 is formed by connecting a tooth-shaped outer contour curve and a smooth curve, a curve a connecting the tooth-shaped top ends of the roller 1 is a first curve, a curve b is a second curve, the first curve a is close to the large end of the roller 1 on the generatrix of the roller 1, a connecting line between two ends of the first curve is a first central line n, the second curve b is close to the small end of the roller 1 on the generatrix of the roller 1, a connecting line between two ends of the second curve is a second central line s, and an included angle between the first central line and the second central line, namely an included angle theta of a hyperboloid of the roller 1 is 7 degrees; one surface of the guide plate 2 is set to be a curved surface; the diameter D of the large end of the roller 1 is 410mm, and the diameter D of the small end of the roller 1 is 260 mm; the spiral shape of the roll 1 is shown in fig. 2, and the tooth profile outer contour parameters are as follows: the pitch P is 16mm, and the tooth radius R is 6 mm; the pitch is the distance between the corresponding points of two adjacent tooth crests, and the tooth form radius is any line segment from the center of the tooth form to the tooth form arc.
As shown in fig. 1, the first curve is an arbitrary curve between m and p, and a point on the first curve is not more than 10mm in maximum distance from the first central line, the second curve is an arbitrary curve between q and t, and a point on the second curve is not more than 5mm in maximum distance from the second central line;
2) constructing a deformation zone: arranging the two guide plates 2 oppositely on the surface with the curved surface, arranging the two guide plates 2 between the rollers 1, and forming a deformation area by the two guide plates 2 and the two rollers 1;
the area of the deformation area corresponding to the curved surface formed by the tooth-shaped outer contour curve of the roller 1 rotating around the axis of the roller 1 is a rolling area, the distance between the inner threads of the rolling area is decreased progressively, and the area of the deformation area corresponding to the curved surface formed by the second curve of the roller 1 rotating around the axis of the roller 1 is a rounding area; the length of the rolling area is 3 times of the length of the rounding area;
3) constructing an equiovality deformation zone: the ovality in the deformation zone is kept unchanged; ovality was 1.05;
4) selecting a rolling feeding mode: the reverse rolling mode is that the blank 3 enters a deformation zone from the large end of the roller 1 in the rolling process;
5) selecting materials, purchasing 2219 aluminum alloy bar with the diameter of 94 × 400mm, wherein the bar is obtained by a manufacturer through smelting, forging and machining in a vacuum consumable arc furnace, the quality meets the rolling requirement, the tissues of all parts of the cylindrical blank 3 are uniformly distributed, and the defects of inclusions, air holes and the like are not found;
6) rolling, namely respectively rotating two rollers 1 around the central axes thereof, heating a blank 3 in a heating furnace at the heating temperature of 415 ℃ for 70min, transferring the 2219 aluminum alloy bar heated to the temperature from the heating furnace into a material guide groove of a rolling mill for 8s, wherein the technological parameters of the rolling process comprise that the taper angle inclination α of the roller surface in a deformation zone is 3.5 degrees, the feed angle β is 23.5 degrees, the rolling angle gamma is 20.5 degrees, the diameter reduction rate epsilon is 56 percent, the rotating speed n of the rollers 1 is 40r/min, the blank 3 enters from the deformation zone between the large ends of the rollers 1 and starts to be rolled, the blank 3 spirally advances in the deformation zone until being output from the deformation zone between the small ends of the rollers 1, and the rolling process is completed VxThe blank 3 after the rolling is finished is cooled to the room temperature in air as the blank feeding speed;
the initial structure is shown in FIG. 6, in which the average size of the grains is 75 μm; by adopting the method of the invention, FIG. 7 shows the microstructure of the rolled aluminum alloy, wherein the grain size is about 2.4 μm, and the grain refinement degree is 96.8%.
Claims (6)
1. A reverse-cone spiral roller superfine crystal rolling method for large-size aluminum alloy bars comprises the following steps:
1) the design of rolling tool specifically includes roll design and baffle design, sets up the roll into hyperbolic face class round platform shape spiral roller, specifically is: the generatrix of the roller is formed by connecting a tooth-shaped outer contour curve and a section of smooth curve; setting one surface of the guide plate as a curved surface;
2) constructing a deformation zone: the curved surfaces of the two guide plates are oppositely arranged, the two rollers are arranged between the guide plates, and the area enclosed by the two guide plates and the two rollers is a deformation area;
3) constructing an equiovality deformation zone: the ovality in the deformation zone is kept unchanged;
4) selecting a rolling feeding mode: the reverse rolling mode is that the blank enters a deformation zone from the large end of a roller in the rolling process;
5) selecting materials: selecting 2219 aluminum alloy blanks with the diameter of 60-500mm and the length of 300-15000 mm;
6) rolling: the two rollers respectively rotate around the central axes thereof, after the blank is heated, the heated blank is sent into the deformation zone according to the rolling feeding mode, the blank spirally advances in the deformation zone and is output from the small ends of the rollers, the variable cross-section rolling is realized, and after the rolling process is finished, the blank is cooled.
2. The method of claim 1, wherein the curved line connecting the tooth-shaped top ends of the rolls is a first curved line, the line between the two ends of the first curved line is a first center line, the curve on the roll generatrix near the small end is a second curved line, and the line between the two ends of the second curved line is a second center line;
the maximum distance between a point on the first curve and the first middle line is not more than 10mm, and the maximum distance between a point on the second curve and the second middle line is not more than 5 mm;
an included angle between the first central line and the second central line is 4-7 degrees.
3. The method of claim 2, wherein the area of the deformed area corresponding to the curved surface formed by the tooth-shaped outer contour curve of the roll rotating around the roll axis is a rolling area, the pitch of the spiral lines in the rolling area decreases, and the area of the deformed area corresponding to the curved surface formed by the second curve of the roll rotating around the roll axis is a rounding area; the length of the rolling area is 2.5-5 times of the length of the rounding area.
4. The method for ultrafinely rolling the reverse tapered helical roller of the large-sized aluminum alloy bar as claimed in claim 1, wherein the diameter of the large end of the roller is 3-6 times of the diameter of the billet, and the diameter of the small end of the roller is 2.5-4 times of the diameter of the billet.
5. The method of claim 1, wherein the ovality is the ratio of the maximum distance between the two guide plates and the distance between the two rolls in the same cross section of the deformation zone, and the ovality is equal at any cross section of the deformation zone, and the ovality is 1.05 to 1.07.
6. The method as claimed in claim 1, wherein the heating of the billet is carried out by heating the billet in a heating furnace at 390-470 ℃ for T = Db× (0.6-0.8) min, wherein D isbIs the diameter of the blank in mm;
the taper angle α of the roll surface in the deformation zone is 3.5-4.5 degrees, the feed angle β is 21.5-23.5 degrees, the rolling angle gamma is 18.5-20.5 degrees, the rotating speed n of the roll is 40-68R/min, the diameter reduction rate epsilon is 45-62 percent, the tooth profile outer contour parameters are that the screw pitch P is 14-23mm, and the tooth profile radius R is 6-9 mm;
and the blank cooling is blank air cooling or blank water cooling to room temperature.
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CN104971940A (en) * | 2014-04-14 | 2015-10-14 | 西安中泰新材料科技有限公司 | Screw rolling method and screw rolling device for titanium rod |
CN108405607A (en) * | 2018-03-01 | 2018-08-17 | 西安东耘新金属材料有限公司 | A kind of isometric helix milling method of large-sized aluminium alloy ultra fine grained steel bar |
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