RU2112612C1 - Method for rolling articles with predetermined curvature - Google Patents

Abstract

FIELD: plastic metal working, namely, manufacture of flat articles with predetermined curvature such as discs. SUBSTANCE: method comprises steps of reducing blank in rolls with cone barrels mounted in such a way that axes of barrel cones crosses at side of small bases of cones; checking curvature of article at roll outlet and correcting it. Novelty is rolling heated blank. Curvature correction is realized due to temperature change according to admissible heating range of blank material. Relation between heating temperature, mean rate of article at roll outlet, width of article, difference of rates of lateral edges of article and objective curvature radius is mathematically normalized. EFFECT: enhanced efficiency. 3 dwg

Description

 The invention relates to the processing of metals by pressure in the field of ferrous metallurgy and is intended for the manufacture of products with a given curvature such as flat disks.

 A known method of rolling wedge-shaped profiles [1] in rolls with a conical barrel, in which the rolls are set at an angle to each other with the intersection of their axes from the side of the smaller diameter of the rolls, and the workpiece on the same side is crimped to a greater extent than from the opposite.

 A significant disadvantage of this method is the impossibility of changing the parameters of the rolling process without changing the geometry of the tool and the size of the workpiece, which reduces the yield and increases the complexity of manufacturing (rolling) of products.

 Closest to the claimed technical solution is a method of rolling wedge-shaped profiles [2], which includes rolling the workpiece in conical rolls and applying a backing force to a less crimped edge using an additional roller, changing the speed of rotation of which affects the grayness of the rolled product.

 The disadvantage of the closest solution is the low productivity associated with the time it takes to set up the equipment and subsequent additional editing operations.

 The task of the invention is to remedy this drawback, namely the reduction of additional operations and reduction of equipment setup time.

,
где
ρ - радиус кривизны изделия;
T₀ - начальная температура прокатки, равная средней температуре диапазона нагрева заготовки для прокатки;
V_1ср - средняя скорость изделия на выходе из валков;
b₁ - ширина изделия;
Δt - изменение температуры заготовки при коррекции кривизны изделия;
Δv₁ - разность скоростей изделия по боковым кромкам.The problem is achieved in that in the method of rolling products of a given curvature, including the compression of the workpiece in work rolls with conical barrels installed with the intersection of their axes on the side of the small bases of the cones of the barrels, control of the curvature of the product at the exit of the rolls, according to the invention, the rolling is carried out with heating, and the correction of the curvature of the profile is carried out by changing the temperature of the workpiece within the heating range of this material of the workpiece for rolling according to the following relationship:

,
Where
ρ is the radius of curvature of the product;
T ₀ - the initial rolling temperature equal to the average temperature of the heating range of the billet for rolling;
V _1av - the average speed of the product at the exit of the rolls;
b ₁ is the width of the product;
Δt is the change in the temperature of the workpiece during correction of the curvature of the product;
Δv ₁ - the speed difference of the product along the lateral edges.

, позволяет без нарушения геометрии калибра, т.е. на одном комплекте рабочих валков осуществить регулирование кривизны изделия в широких пределах, чего нельзя достичь с помощью подпирающего ролика, изменяя его скорость вращения, так как изменение скорости подпирающего ролика в широких пределах приводит к значительным усилиям, действующим на заготовку в направлении, перпендикулярном продольному направлению деформации и ее смещению в указанном направлении, и соответственно к искажению геометрических размеров деформируемого изделия, т. е. к браку и снижению выхода годного. Кроме того, предлагаемый способ исключает перенастройку кинематической связи рабочих валков и системы контроля с учетом изменения кинематических параметров процесса деформации по сравнению с рассмотренными ранее аналогами и прототипом, что также увеличивает производительность за счет сокращения дополнительных операций переналадки оборудования и систем контроля параметров процесса прокатки изделий заданной кривизны.An increase in the temperature of processing a workpiece with an increase in the radius of curvature of a product from a predetermined one and a decrease in temperature of a workpiece with a decrease in radius of curvature of a product from a predetermined one according to the dependence

, allows without violating the geometry of the caliber, i.e. on one set of work rolls to regulate the curvature of the product over a wide range, which cannot be achieved with the support roller, changing its rotation speed, since changing the speed of the support roller over a wide range leads to significant forces acting on the workpiece in a direction perpendicular to the longitudinal direction of deformation and its displacement in the indicated direction, and, accordingly, to the distortion of the geometric dimensions of the deformable product, i.e., to marriage and reduced yield. In addition, the proposed method eliminates the reconfiguration of the kinematic connection of the work rolls and the control system, taking into account changes in the kinematic parameters of the deformation process compared to the analogues and prototype discussed earlier, which also increases productivity by reducing the additional operations of readjusting equipment and systems for controlling the parameters of the rolling process of products of a given curvature .

 In FIG. 1 shows the deformation zone from the side of the small bases of the cones of the roll barrels; in FIG. 2 - cross section of the deformation zone; in FIG. 3 is a plan view of the deformation zone.

The method is as follows. Work rolls 1 and 2 with conical barrels are installed at an angle φ _{1 to} each other so that the axis of the rolls 1 and 2 are mutually intersected from the side of the small bases of the roll barrels. Work rolls have the same geometric dimensions and the angle φ _{2 of the} cone of the roll barrel is equal to the angle φ _{1 of the} inclination of the axes of the rolls. A variant of using a set of rolls with different geometric dimensions is possible. The deformation zone is formed by parallel generators of the cones of the roll barrels, while the rectangular workpiece is uniformly crimped in width.

, где l₁ и l₂ - соответственно длины очага деформации по правой 4 и левой 5 кромкам заготовки 3; b_o - ширина заготовки.The deformation zone abcd (Fig. 3) is limited at the input cd by the plane N, and at the exit ab, by the plane M. The position of the plane N of the entrance of the workpiece 3 to the deformation zone is determined by the formula

where l ₁ and l ₂ - respectively, the length of the deformation zone along the right 4 and left 5 edges of the workpiece 3; b _o - the width of the workpiece.

 A change in the angle of the task of the strip into the rolls is accompanied in known solutions by a change in the working width included in the strip rolls. In order to eliminate this fact, which leads to a change in the geometric dimensions of the cross section emerging from the product rolls, which requires additional calibration calculations, process adjustment, and ultimately increases the complexity of manufacturing products, the angle of the workpiece in the rolls is assumed to be constant for each particular product and does not change during the rolling process.

 Before rolling the billet is heated to an initial temperature equal to half the minimum and maximum processing temperatures of this material billet.

 The radius of curvature of the product is controlled using contact messdoz.

 When rolling in conical rolls, the radius of curvature of the product can vary widely depending on the angle of inclination of the axis of the rolls on the angle of taper of the roll barrels, the accuracy of the geometric dimensions of the workpiece, etc. The multifunctional dependence of the rolling process in conical rolls does not allow, in a known manner, to provide a technological process for producing products with exact geometric dimensions. Therefore, when changing the radius of curvature of the product due to, for example, the above reasons, the kinematics of the metal flow in the deformation zone is affected by measuring the temperature of the workpiece entering the rolls.

.At the initial moment of rolling the product, when a part of the product comes out from the rolls, sufficient to measure its curvature using known devices, for example contact messdozas interacting with the strip leaving the rolls, and according to the magnitude of the mass dose delivered to the control system of the heating device, the temperature is changed heating the workpiece in the temperature range of the processing of this material according to the dependence obtained empirically:

.

 When changing the heating temperature of the workpiece due to changes in friction conditions in the deformation zone, the resistance of plastic deformation materials and other parameters of the rolling process, the critical line ef (Fig. 3) will change its position and rotate around point O by a certain angle and take the position e'f ' . In this case, a change in the ratio of advance zones from the side of the inner 5 and outer 4 edges of the product, i.e. the lead zone, for example, from the side of the outer edge 4 of the product will increase and will have a value bf ', and the lead zone from the side of the inner 5 edge of the product will decrease and will have the value ae', based on which the metal speed from the side of the outer 4 edge of the product will increase, and the metal speed from the side of the inner 5 edge of the product will decrease and the radius ρ of curvature of the product will accordingly decrease.

 The rotation of the critical line ef occurs as a result of the redistribution of the tangential friction forces in the advance zones and the lag of the deformation zone due to the conicity of the rolls and their installation with the intersection of the axes from the side of the small bases of the roll barrels. When rolling in conical rolls, there is a combination of the angular rotation of the critical line ef and its movement along the deformation zone. However, only the rotation of the critical line ef significantly affects the change in the radius of curvature of the product, as a result of which there is a change in the ratio of metal velocities along the edges of the strip at the exit of the product from the rolls.

On a laboratory rolling mill SPKN-110M with conical rolls (the diameter of the large base of the rolls is 110 mm) installed with the intersection of their axes at an angle of 30 ^o , this method is used to roll a blank of a flat disk with a cross-sectional size of 3 • 45 mm and an average diameter of 270 mm from the original rectilinear strip of rectangular section 5 • 44 mm. The strip material is steel 20. The initial straight strip had a thickness tolerance of 5 $\genfrac{}{}{0ex}{}{\text{+0.25}}{\text{-0.3}}$ mm, and with a smooth change in the tolerance along the length of the strip from its minimum value (-0.3 mm) to its maximum value (+0.25), which may be due either to the beating of the rolls of the stand in which it was not received, or the strip is taken from the ends of the strip having different rolling temperatures, and thereby ensuring due to the "spring" of the working stand, a smooth change in the thickness of the initial strip along its length in the above ranges. Therefore, when rolling an annular product from such a workpiece, its radius of curvature changes depending on changes in the thickness of the workpiece along its length; therefore, so that the radius of curvature of the product remains constant, the inventive method involves the need for a smooth change in the temperature of the strip (billet) at its entrance to the rolls in accordance with a change in its thickness within the specified tolerance.

The initial temperature (T ₀ ) of rolling is 1000 ^o C. When rolling an annular product from the specified workpiece at a temperature of 1000 ^o C, the radius of curvature decreased from the set value (ρ = 135 mm) with a strip thickness with a maximum tolerance value (+0.25 mm) of 5 mm, and with a strip thickness with a minimum tolerance value (-0.3 mm), the radius of curvature of the product increased by 6.2 mm. To reduce the radius of curvature to the required temperature, the workpiece temperature during the rolling process of the product is gradually increased by 35 ^o C. To increase the radius to the required temperature, the workpiece temperature is gradually reduced by 40 ^o C.

 The proposed technical solution can be used to obtain long and shaped profiles, especially asymmetric in the metallurgical industry.

Claims (1)

The method of rolling products of a given curvature, including the compression of the workpiece in work rolls with conical barrels installed with the intersection of their axes on the side of the small bases of the barrel cones, control of the curvature of the products at the exit of the rolls, characterized in that the rolling is carried out with heating, and the profile curvature is corrected by changing the temperature of the workpiece within the heating range of this material, the workpiece for rolling according to the following relationship:

where ρ is the radius of curvature of the product;
T ₀ - the initial rolling temperature equal to the average temperature of the heating range of the billet for rolling;
V _1av - the average speed of the product at the exit of the rolls;
b ₁ is the width of the product;
Δt is the change in the temperature of the workpiece during correction of the curvature of the product;
ΔV ₁ - the difference between the speeds of the product along the lateral edges.

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