RU2009733C1 - Method of round rods manufacture by rolling - Google Patents

Abstract

FIELD: metallurgy. SUBSTANCE: ratio of eccentricity of rollers and diameter of pass and engagement of the parameters with flattering angle are regulated in three roller pass during screw type rolling. EFFECT: recommended ratio ensures to roll hard deforming materials with good quality. 2 cl, 3 tbl

Description

 The invention relates to the processing of metals by pressure and relates to a technology for producing round bars by rolling, mainly from alloyed metals and alloys.

 A known method of producing round rods by longitudinal rolling [1]. The main disadvantages of this method include the weak development of metal over the cross section, low surface quality, as a result of low yield or production of rods from alloyed metals and alloys. These shortcomings are caused by a low exhaust hood and conditions of metal forming, in which the formation of surface defects is inevitable and the compaction of the central zone is difficult.

 Known methods for producing round rods by helical rolling, for example [2-4]. The axial component of the peripheral velocity vector in them can be obtained by one of various methods [5]: by turning the rolls at the feed angle; the eccentricity of the installation of rolls inclined at an angle of rolling.

 The first group includes, in particular, a method for producing round rods by rolling, including deformation of the workpiece by rolls deployed at a feed angle of 20–45 with compression in a passage of 20–50 [2].

 When alloyed metals and alloys having reduced ductility are rolled by this method, massive damage by tearing of the surface and peripheral layers of the metal is inevitable.

 The cause of breaks is the circumferential and radial tensile stresses that accompany the sharp plastic bending of the free surface of the deformable metal in the zone between the rolls. Realized in the known method, high single reductions, intensifying the displacement of the metal into the gaps, bring tensile stresses to exorbitant values at which ruptures of the alloyed metal are inevitable.

 In addition, the implementation of the rolling method in rolls deployed at the feed angle is associated with the use of complex and relatively weak spindle gears with a high skew angle. When processing alloyed metals, especially in small diameters, the low strength of the main line spindles passes from a structural factor to a technological factor that limits deformation and, therefore, the quality of the metal.

It should be borne in mind that the most modern technical solutions in the field of helical rolling of continuous billets require a proportionate choice of parameters characterizing the spatial position of the rolls and the billet relative to each other. For example, a method [3] as an essential distinctive features not only contains the value of the angle β = 3-20 supply ^about, the angle δ = 0-10 reeling out ^of, but their total value β + δ = 5-30 ^of expressing the proportionality between them.

 The closest technical solution is a method for producing round rods by rolling, including deformation of the workpiece in a gauge formed by three rolls having an eccentricity and rotated by an angle of rolling [4].

= 0,6-0,8, угол раскатки валков δ выдерживается в пределах 0,8-1,05 рад. (45-60^о). Важное значение в формировании кинематических и деформационных условий прокатки, прямо влияющих на выход годного, имеют величина

и соотношение между

и радианной мерой угла раскатки δ _(рад). В известном способе угол раскатки δ _(рад) больше 0,6

.In the known method, the magnitude of the eccentricity Δ is not more than 0.6-40.8 caliber diameters d _to , i.e., the relative eccentricity in fractions of the caliber is

= 0.6-0.8, the roll expansion angle δ is maintained in the range of 0.8-1.05 rad. (45-60 ^o ). Of great importance in the formation of kinematic and deformation conditions of rolling, which directly affect the yield, are

and the relationship between

and a radian measure of the rolling angle δ _(rad) . In the known method, the rolling angle δ _{(rad) is} greater than 0.6

.

 The disadvantage is the low yield when processing alloyed metals and alloys.

 The aim of the invention is to increase the yield when processing alloyed metals and alloys.

 This is achieved by the fact that, in the method for producing round rods by rolling, including deformation of the workpiece in a gauge formed by three rolls having an eccentricity and rotated by an angle of rolling, according to the invention, the workpiece is deformed with a ratio of roll eccentricity to a diameter of 1.2-3.3.

(рад); (1)
δ +

≅ 3,7 (2) где δ - угол раскатки, рад;
Δ - эксцентриситет валков;
d_к - диаметр калибра;
А= 0,08-0,35 коэффициент пропорциональности, учитывающий склонность легированного металла к поперечной раскатке.This goal is also achieved by the fact that the deformation of the workpiece is carried out with the ratios of the angle of rolling, the eccentricity of the rolls and the diameter of the caliber,
δ = A

(glad); (1)
δ +

≅ 3.7 (2) where δ is the rolling angle, rad;
Δ is the eccentricity of the rolls;
d _{to the} diameter of the caliber;
A = 0.08-0.35 coefficient of proportionality, taking into account the tendency of the alloyed metal to transverse rolling.

The method is as follows. A billet of alloyed metal or alloy is heated to a temperature of deformation according to its composition and is supplied for rolling. During rolling, the workpiece is deformed in a gauge formed by three rolls installed with an eccentricity, the value of which Δ exceeds the diameter of the caliber d _to 1.2-3.3 times. Work rolls deforming the workpiece are rotated through an angle of rolling.

To perform the functional purpose, the rolling rolls are equipped with at least two main working sections; crimp and gauge. The crimp sections of the three rolls form a conical deformation zone in which the workpiece is crimped in diameter. The angle of taper deformation zone is kept in the range of ^about 10-20. The calibrating sections of the rolls form a caliber of constant diameter d _k , in which a geometrically regular round profile of high accuracy is formed, the straightness of the forming rod and the given surface relief are ensured.

 The degree of deformation, the frequency of rotation of the work rolls are set according to the level of plastic properties of the alloyed metal. For most alloyed metals and alloys, they are, respectively, in the range of 30-80 and 40-100 rpm.

The diameter of the rolls D _In should be taken equal to at least two diameters of caliber dk. This ensures uniformity of metal working over the cross section and stable grip of the workpiece. The upper limit of the ratio D _B / d _to is close to six and is strictly limited by the condition of the arch of three rolls to a minimum caliber.

 The experimental data are presented in table. 1 p. 3.

 The eccentricity of the rolls within 1.2-3.3 caliber diameters provides the necessary rotation of the vector of the peripheral speed of the rolls to the rolling axis. In this case, forced axial outflow of the metal is actively stimulated and its lateral displacement into the gaps between the rolls is limited. The level of partial reductions is established, which reliably ensures the penetration of shear plastic deformation to the entire depth of the cross section, when forming a stable scheme of comprehensive compression in the entire volume of the workpiece, including in the central zone. The outer surface of the deformation zone is characterized by the absence of sharp bends of small radius. The trajectory of the metal in the inter-roll zones of non-contact deformation is quite smooth. Tensile stresses in the peripheral layers and on the surface of the workpiece in the roll gaps are minimized at a level close to zero.

 The kinematic conditions created in the source and the stress-strain state are most favorable for the most complete use of the natural resource of plasticity of the alloyed metal. Subjected to intense shear deformation due to axial feed, the metal is worked out and compacted evenly over the entire cross section. Signs of foci of overstrain and loosening are absent in the entire volume of the workpiece. The receipt of high-quality rolled metal from alloyed metal is guaranteed by the entire course of its deformation in the proposed method.

In addition, the high eccentricity of the rolls contains the ability to reduce the rolling angle to 0.15-0.50 rad. (10-30 ^o ). In this case, conditions are created for choosing the length of the gage section without regard to design limitations. The criterion for assigning the length of the calibrating section remains exclusively the required geometric accuracy of the rods.

 According to experiments, the accuracy of the rods in the new method is not less than 6-8 times higher compared to the prototype. The two-support design of the roll units also contributes to an increase in accuracy.

за нижний предел способ приобретает недостатки прототипа, связанные с локализацией деформации в периферийных слоях и действием сопутствующих ей растягивающих напряжений в центральной зоне. Верхний предел определен конструктивными возможностями трехвалковой схемы прокатки. Реализация

>3,3 конструктивно практически невозможна по условию сведения валков на минимальный калибр. Образование калибра диаметром d_к тремя валками диаметром D_в возможно только при эксцентриситете валков, не превышающем Δ≅

(D_в+d_к).At the lower limit, the eccentricity is limited by the level of the axial feed, which ensures through penetration of intense plastic deformation and reliable suppression of axial tensile stresses. With a decrease

beyond the lower limit, the method acquires the disadvantages of the prototype associated with the localization of deformation in the peripheral layers and the action of the accompanying tensile stresses in the Central zone. The upper limit is determined by the design capabilities of the three-roll rolling scheme. Implementation

> 3.3 structurally virtually impossible by the condition of rolls to a minimum caliber. The formation of a caliber of diameter d _to three rolls of diameter D _{in is} possible only with an eccentricity of the rolls not exceeding Δ≅

(D _in + d _to ).

не выходит за пределы 3,3. Отрицательных явлений и потери положительного эффекта на верхнем пределе эксцентриситета не обнаружено.Given the fact that with the complete reduction of three rolls having an angle of expansion, the ratio of D _in / d _to practically does not exceed 5.6, the maximum value

does not go beyond 3.3. Negative phenomena and the loss of a positive effect at the upper limit of the eccentricity were not found.

, как фактора, управляющего осевыми истечениями, уровнем частных обжатий и глубиной проработки сечения прутка.Depending on the level of continuity of the metal of the initial billet, it is possible to rationalize the magnitude of the eccentricity of the rolls

as a factor that controls axial outflows, the level of partial reductions, and the depth of development of the bar section.

= 2,6-3,3.Continuously cast billets, open-cast ingots, which are characterized by the greatest friability and imperfection of the axial zone, are required to be rolled at maximum plastic deformations and compression stresses in the central part of the roll. Such rolling conditions are realized with the greatest eccentricity of the rolls.

= 2.6-3.3.

= 1,9-2,6.Dense ingots after improving remelts (VDP, ESR, etc.) are allowed to deform under conditions with

= 1.9-2.6.

= 1,2-1,9 целесообразна для получения проката из плотного, в основном предварительно деформированного металла.Lower part of the interval

= 1.2-1.9 is appropriate for the production of rolled products from a dense, mainly pre-deformed metal.

 The limits of the interval by the coefficient A of the formula (1) maintain the kinematic balance described above in the quality that ensures the creation of the desired technical result.

 According to experimental data (Table 2), violation of the upper boundary A = 0.35 excessively increases the angle of rolling. The rolling process acquires the disadvantages of the prototype associated with the violation of the kinematic balance between the growth of the kinematic pressure from the side of the cup-shaped rolls and the flap of the vector of the peripheral speed of the rolls from the axial direction. As in the prototype, lateral displacement of the metal is forcibly activated, the curvature of the plastic bending of the free surface of the roll in the gap between the rollers grows, and the formation of numerous foci of discontinuity is initiated in the peripheral layers.

в сумме с δ _(рад). В заявленных пределах существует технический результат. Однако область значений за нижним пределом А<0,08 несоразмерно снижает долю угла раскатки и увеличивает долю эксцентриситета. Процесс прокатки характеризуется увеличением осевой составляющей скорости валков и металла, не сбалансированной с уменьшением кинематического подпора со стороны слабоконусных чашевидных валков. Процесс из кинематически равновесного состояния переходит в состояние с кинематическим осевым натяжением. В большей части объема очага деформации возникают осевые растягивающие напряжения, которые не только исключают уплотнение легированного металла, залечивание рыхлостей и пустот, но и могут быть непосредственным инициатором образования новых осевых разрывов. Получаемый прокат имеет не кондиционную по плотности макро- и микроструктуру в целом по объему.Decreasing A increases the proportion

in total with δ _(rad) . Within the claimed limits there is a technical result. However, the range of values beyond the lower limit A <0.08 disproportionately reduces the proportion of the rolling angle and increases the proportion of eccentricity. The rolling process is characterized by an increase in the axial component of the speed of the rolls and metal, which is not balanced with a decrease in kinematic back pressure from the side of the slightly conical cup-shaped rolls. The process from a kinematically equilibrium state passes into a state with kinematic axial tension. In most of the volume of the deformation zone, axial tensile stresses arise, which not only exclude compaction of the alloyed metal, healing of friable and voids, but can also be a direct initiator of the formation of new axial discontinuities. The resulting steel has a non-conditional density macro- and microstructure as a whole in volume.

+ δ удерживает общий уровень осевой подачи. С нарушением его осевая подача чрезмерно интенсифицируется, что приводит к резкому ухудшению условия вращения заготовки. Экспериментально установлено (табл. 3), что превышение суммы значения 3,7 вызывает сильное тангенциальное скольжение (уменьшение коэффициента тангенциальной скорости до значений близких к 0) со случаями полной блокировки вращения заготовки и остановки процесса. Одновременно ухудшается калибровка профиля. Нижнее значение суммы не имеет отдельного физического смысла, соответствует нижним значениям

= 1,2; А= 0,08 и составляет 1,3.Restriction (2) on the amount

+ δ holds the overall axial feed rate. With a violation, its axial feed is excessively intensified, which leads to a sharp deterioration in the condition of rotation of the workpiece. It was experimentally established (Table 3) that an excess of the sum of 3.7 causes a strong tangential slip (a decrease in the tangential velocity coefficient to values close to 0) with cases of complete blocking of the workpiece rotation and stopping the process. At the same time, profile calibration is degraded. The lower value of the sum has no separate physical meaning, corresponds to the lower values

= 1.2; A = 0.08 and is 1.3.

 The specific value of coefficient A is determined by the tendency of the alloyed metal to transverse rolling during screw rolling, which, ceteris paribus, determines the volume of metal displaced into the roll gaps, plastic bending of the outer contour of the deformation zone, and through this amplitude, stress level of alternating bending, the risk of fracture and exit fit.

According to the tendency to lateral deformation during helical rolling, the bulk of alloyed metals and alloys can be divided into three groups:
a group of low-expanding alloys exhibiting a pronounced tendency to longitudinal outflow in the direction of the main deformation. This group consists mainly of metals and alloys with pronounced elastic and limited viscous properties, such as heat-resistant nickel alloys such as ХН51ВТЮКФР, high-speed steels P6M5, etc. For them, A = 0.26-0.35;
the middle group of alloys, which is characterized by an increased predisposition to broadening. It includes, in particular, titanium alloys of the VT-31, VT-14 type, zirconium-based alloys, heat-resistant steels of the type 45X14H14V2M, 40X9C2 and others. This group corresponds to A = 0.17-0.26; a group of highly expandable alloys with the greatest tendency to transverse outflow in the deformation zone, for example, corrosion-resistant steels of the type 15X25T, X17H2, titanium alloys of the grades 3M, 3B, etc. Billet rolling from these metals should be carried out at A = 0.08-0.17.

PRI me R 1. The method is implemented on an experimental mill for producing rods with a diameter of 40 mm from heat-resistant austenitic steel 45X14N14V2M. The rods were obtained from experimental ingots of open arc smelting, ingots of electroslag remelting and previously deformed billets. The diameter of the initial ingots and billets was 85 mm. The rods were obtained by rolling in rolls with a diameter of 220 mm, installed at an angle of rolling of 0.35 rad (20 ^about ), a diameter of 40 mm caliber. Eccentricity of rolls 132; 80; 48 mm according to the condition of the initial blanks in the above order, while the ratio Δ / _d to respectively 3.3; 2.0; 1,2. By rolling the ingots and billets were heated to 1160 ^C. Rolling held stably without formation of macro- and micro-defects. The resulting rods were characterized by a dense, well-developed structure, high accuracy of geometric dimensions. Regulatory requirements are fully implemented. Technological waste consisted only of the end trim of the flipped ends.

PRI me R 2. The proposed method according to p. 2 of the formula is implemented on an experimental mill for producing rolled products with a diameter of 40 mm. Experimental ingots and billets with a diameter of 80 mm of the following grades and production methods were used as the starting material:
ingot of open arc smelting from corrosion-resistant steel 12X18H10OT;
a vacuum arc remelting ingot from VT-14 titanium alloy;
pre-pressed billet made of heat-resistant nickel-base alloy ХН51ВМТЮКФР.

Before rolling, the billets were heated in a chamber electric furnace of resistance to the temperature of greatest deformability during screw rolling. Specifically, the heating temperature on marks made: 12X18H10T - 1190 ^C; BT-14 - 1160 ^{° C;} ХН51ВМТЮКФР - 1140 ^о С.

 Billets (ingots) were rolled in a three-roll caliber formed by rolls installed with a relative eccentricity: 3.3 for 12Kh18N10T steel ingots; 2.0 for ingots from VT-14 alloy and 1.2 for deformed billets from KhN51VMTYUKFR alloy.

The rolls were installed at an angle of rolling, satisfying relations (1), (2), taking into account the choice of coefficient A, respectively, of the alloy grade. The rolling angle was for: steel 12X18H10T (A = 0.08) - 0.26 rad. (15 °); VT-14 titanium alloy (A = 0.20) - 0.40 rad. (23 ^o ); KhN51VMTYUKFR alloy (A = 0.35) - 0.42 rad. (25 ^o ). The diameter of the rolls along the calibrating section was 220 mm. The angle of inclination of the generatrix of the crimp section to the axis of rolling was kept within 12 °.

 The rolling process proceeded stably without deviations. In the obtained rods, a dense, uniformly worked out structure is fixed. Traces of cast structure and tears of rolling origin are completely absent. The geometric accuracy of the profile exceeds the requirements for high precision rental. The yield growth in comparison with the prototype is at least 20-25%, depending on the brand. (56) 1. Bakhtinov V. B., Rolling production, M.: Metallurgy, 1987, p. 206-208.

 2. Copyright certificate of the USSR N 500822, cl. B 21 B 19/00, 1976.

 3. Japanese application N 59-225802, cl. B 21 V 1/16, 13/00, 1984.

 4. Tselikov A.I., Barbarich M.V., Vasilchikov M.V. et al. Special rolling mills / M.: Metallurgy, 1971, p. 12-13.

 5. Teterin P. K. Theory of transverse and helical rolling, M.: Metallurgy, 1983, p. 82, 83.

Claims (2)

 1. METHOD FOR PRODUCING ROUND RODS BY ROLLING, including deforming a workpiece in a caliber formed by three rolls having an eccentricity and rotated by an angle of rolling, characterized in that the workpiece is deformed with respect to the eccentricity of the rolls of 1.2 to 3. 2. The method according to p. 1, characterized in that the workpiece is deformed for the ratio of the angle of expansion, the eccentricity of the rolls and the diameter of the caliber
δ = A (Δ / d _k ),
δ + Δ / d _k ≅ 3.7,
where δ is the rolling angle, rad;
Δ is the eccentricity of the rolls;
d _{to the} diameter of the caliber;
A = 0.08 - 0.35 - coefficient of proportionality, taking into account the tendency of the alloyed metal to transverse rolling.

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