RU2031750C1 - Centering device to tube mill - Google Patents

Abstract

FIELD: rolling. SUBSTANCE: centering device has two levers installed on pivots in a casing. One lever is provided with two centering rollers. The other one is provided with one centering roller. The levers have a synchronizing link to interconnect them as a hinge. In doing so the angle between two lines connecting centers of the rollers of two-roller lever and passing through a pivot of the lever and roller center being nearest to this pivot is determined by mathematical dependency between geometric parameters of the device and centering article. EFFECT: increased accuracy of centering. 4 dwg

Description

 The invention relates to the field of metal forming, and more specifically to devices for centering rolled products. The invention can most effectively be used in tube rolling mills for centering a rolling rod or tube round billet.

 Known centering rod with a mandrel, comprising a housing, an upper lever with a centering roller, a lower lever with a pair of similar rollers and individual lever rotation drives that work towards each other [1].

 To maintain centering accuracy, the drive force of the lower arm must always exceed the drive force of the clamp of the upper arm.

 However, the high temperature on the rolled metal side and a significant amount of scale, on the one hand, change the conditions in the centering knots, increasing the resistance to rotation of the upper and lower levers, and on the other hand, lead to uneven wear of the sealing assemblies in the drive power cylinders, which means to a drop in the pressure in them and a change in the force developed on the stocks.

 Due to these factors, it is possible to equalize the forces of the clamp drives of the upper and lower rollers, as a result of which the centering axis will begin to “float”, which will lead to additional rod bending, greater vibration, and, therefore, to an unstable position of the mandrel in the deformation zone, bending of the rolling rod and reducing the accuracy of rolled pipes.

 Of the known centralizers of rolling mills, the closest in technical essence is the three-roller centralizer of the tube mill, which contains a housing, two levers, one of which has one centering roller, and the other has two centering rollers, and a synchronizing link [2].

 However, such a constructive embodiment of the centralizer gives the only position of the swing axis of the two-roller lever, the coordinates of which depend on certain values of the radius of the centering roller and the smallest radius of the centering rod. Therefore, when changing the range of diameters of the rod, the centering accuracy is violated, because to ensure it is necessary to change the coordinates of the swing axis of the two-roller lever.

, где r₁ - наименьшее требуемое значение радиуса центрирующего калибра (изделия);
r₂ - наибольшее расчетное значение радиуса центрирующего калибра (изделия);
R - радиус центрирующего ролика;
L - кратчайшее расстояние от центра центрирующего ролика, ближайшего к оси качания двухроликового рычага, до оси качания рычага - вторая координата оси качания;
β - угол между двумя прямыми, одна из которых проходит через центры роликов двухроликового рычага, а вторая - через центр ролика, ближайшего к оси качания двухроликового рычага, и ось качания этого рычага; при этом, наибольшее расчетное значение радиуса центрирующего калибра (изделия) определяется из соотношения
r₂ =

, где r₃ - наибольшее требуемое значение радиуса центрирующего калибра (изделия).In the proposed centering of the tube mill, comprising a housing, two levers, one of which with one centering roller, the other with two centering rollers, the synchronizing link according to the invention, pivotally connecting the levers, the angle β between the straight lines passing, respectively, through the centers of the rollers of the two-roller lever and through the center of the roller closest to the swing axis of the lever, and the swing axis of this lever is determined from the relation
sinβ =

where r ₁ - the smallest required value of the radius of the centering gauge (product);
r ₂ is the largest calculated value of the radius of the centering gauge (product);
R is the radius of the centering roller;
L is the shortest distance from the center of the centering roller closest to the swing axis of the two-roller lever to the swing axis of the lever — the second coordinate of the swing axis;
β is the angle between two straight lines, one of which passes through the centers of the rollers of the two-roll lever, and the second passes through the center of the roller closest to the swing axis of the two-roll lever, and the swing axis of this lever; in this case, the largest calculated value of the radius of the centering gauge (product) is determined from the ratio
r ₂ =

where r ₃ - the largest required value of the radius of the centering gauge (product).

 Such a constructive implementation of the centering of the tube mill provides an increase in the accuracy of centering of the products within the specified ranges, for example, within the ranges Ф 80-160 mm or Ф 60-120 mm with an accuracy of 1 mm.

 The invention is illustrated by drawings, where are presented: in FIG. 1 - centralizer tube mill, in the context; in FIG. 2 - kinematic diagram of a centralizer; in FIG. 3 is a graph of changes in the displacement of the centering axis of the centering rollers relative to the axis of the centered product within the boundary values of the radius of the product; in FIG. 4 - the same, when using the estimated radius of the product when calculating the position of the swing axis of the lever.

 The centralizer of the tube mill comprises a housing 1, an upper lever 2 with a centering roller 3, a lower lever 4 with a pair of similar rollers 5 and 6, a synchronizing articulated link in the form of a lever 7 and an actuator 8 for turning the levers 2 and 4 in the form of a power cylinder.

 The centralizer works as follows.

 The centering rollers 3, 5, 6 under the action of the force of the power cylinder 8 through the levers 2 and 4 and the intermediate link 7 clamp the centered product, forming a tight gauge, and at the end of the rolling process during the reverse stroke of the cylinder are bred.

 The position of the swing axis of the two-roller lever 4 determined by the coordinates calculated depending on the angle according to the claims, allows for greater centering accuracy within a given range of product sizes.

 To simplify the design scheme (figure 2) is considered one two-roller lever, because it is he who determines the accuracy of centering the centralizer. The second lever with one roller is swinging synchronously with the two-roller with the help of synchronizing traction (Fig. 1) or with the help of other technical means (for example, gear sectors). Therefore, in the design seme single-lever lever is not considered.

The initial data for the calculation are:
- r ₁ and r _{2 the} smallest and largest required radius of the roller-centered rolling rod;
- L is the shortest distance from the center of the centering roller closest to the swing axis of the two-roller lever to the swing axis of the lever; selected constructively;
- R≅6r ₁ - radius of the centering roller of the centralizer, determined structurally from the condition of intersection in space;
- centering rollers, reduced to a rolling rod of the smallest radius (r ₁ ), are evenly spaced around a circle with an angle of 120 ^about each other.

 The coordinates a and b of the swing axis E of the two-roll lever (FIG. 2) can be determined using the angle β between the two segments AB and BE connecting, respectively, the centers of the centering rollers of the lever and the center of the roller closest to the swing axis with the swing axis.

 Thus, the angle β is one of the main geometric parameters of the three-roll double-lever centering device and its determination is carried out as follows.

 Consider ΔOWE.

α =

OBE = 180^°-(30^°+β) (1)
По теореме косинусов ОЕ² = ОВ² + ВЕ² - 2˙ОB˙ВЕ˙cos α (2) или OE² = (r₁ + R)² + L² - 2(r₁ + R)L cos (150^o - β) (3) Рассмотрим ΔОВ₁Е.In this triangle: AO = OB = r ₁ + R; BE = L;

α =

OBE = 180 ^° - (30 ^° + β) (1)
By the cosine theorem, OE ² = OB ² + BE ² - 2˙OB˙BEcos cos α (2) or OE ² = (r ₁ + R) ² + L ² - 2 (r ₁ + R) L cos (150 ^o - β) (3) Consider ΔOW ₁ E.

^{α =}

^OB1^{E =}

^β) (4)
По теореме косинусов ОЕ² = ОВ₁ ² + В₁Е² - 2ОВ₁˙ВEcosα , (5) или ОЕ² = (r₂ + R)² + L² - 2(r₂ + R)L˙ cos(180^o -ω-β); (6)
Угол ωопределяется из ΔОА₁В₁ по теореме косинусов
cosω =

; (7) Из

OAB : A₁B₁ = AB
AB = OB ˙cos30^o + AO ˙cos30^o = 2(r₁ + R) cos30^o (8)
Подставляя уравнения (4) и (8) в равенство (7) получаем
cosω =

(9)
Приравнивания правые части равенства (3) и (6) и подставляя значение угла ωиз формулы (9), после необходимых преобразований получаем в окончательном виде
sinβ =

(10)
Соответственно координаты оси качания Е двухроликового рычага в прямоугольной системе координат с началом координат в точке О определяется
a = (r₁ + R) cos30^o + L sin(30^o - β) (11)
b = (r₁ + R) sin30^o + L cos(30^o - β) (12)
Характерной особенностью двухрычажного трехроликового центрователя является то, что он обеспечивает абсолютно точное центрирование только для двух граничных значений радиусов центрируемого стержня r₁ и r₃. Внутри этого диапазона точность центрирования нарушается, что характеризуется смещением Δ оси центрирования роликов центрователя относительно оси центрируемого стержня (фиг.3).In this triangle, OA ₁ = OB ₁ = r ₂ + R
In ₁ E = L

^{α =}

^OB 1 ^{E =}

^β) (4)
By the cosine theorem, OE ² = OB ₁ ² + B ₁ E ² - 2OV ₁ ˙ВEcosα, (5) or ОЕ ² = (r ₂ + R) ² + L ² - 2 (r ₂ + R) L˙ cos (180 ^o - ^ω -β); (6)
The angle ω is determined from ΔОА ₁ В ₁ by the cosine theorem
cosω =

; (7) From

OAB: A ₁ B ₁ = AB
AB = OB ˙cos30 ^o + AO ˙cos30 ^o = 2 (r ₁ + R) cos30 ^o (8)
Substituting equations (4) and (8) into equality (7) we obtain
cosω =

(nine)
Equating the right-hand sides of equality (3) and (6) and substituting the value of the angle ω from formula (9), after the necessary transformations, we obtain the final form
sinβ =

(10)
Accordingly, the coordinates of the swing axis E of the two-roll lever in a rectangular coordinate system with the origin at the point O is determined
a = (r ₁ + R) cos30 ^o + L sin (30 ^o - β) (11)
b = (r ₁ + R) sin30 ^o + L cos (30 ^o - β) (12)
A characteristic feature of the double-lever three-roller centering device is that it provides absolutely accurate centering only for two boundary values of the radii of the centered rod r ₁ and r ₃ . Within this range, the centering accuracy is violated, which is characterized by a shift Δ of the centering axis of the centering rollers relative to the axis of the centered rod (Fig. 3).

(13)
Это позволит располовинить смещение оси центрирования роликов центрователя относительно оси центрируемого стержня (фиг.4).It is graphically established that to increase the accuracy of centering the rods within a given range with boundary values of their radii r ₁ and r ₃ when calculating in formula (10) to determine the coordinates of the swing axis of the two-roll lever, instead of r _3, it is necessary to introduce the calculated radius r ₂ determined from the relation
r ₂ =

(13)
This will halve the offset axis of the centering rollers of the centering device relative to the axis of the centered rod (figure 4).

 An example of a specific application.

=

= 70 мм; R не более 6r₁ = 220 мм;
L = 600 мм.To determine the specific coordinates a and b of the axis of rotation of the two-roller lever of the three-roller centering device with the required smallest and largest values of the radius of the centering rod r ₁ = 40 mm, r ₃ = 80 mm, find: the largest calculated value r _{2 of the} centering rod according to relation (13) and constructively determine the shortest distance L from the center of the centered roller closest to the swing axis of the two-roller lever, and the radius R of the centering rollers
r ₂ =

=

= 70 mm; R no more than 6r ₁ = 220 mm;
L = 600 mm.

i

=
β = 15^°6′
Координаты оси качения Е двуроликового рычага в прямоугольной системе координат с началом координат в точке 0 - оси центрирования определяют по уравнениям (11), (12)
a = (r₁ + R) cos30^o + L˙sin(30^o - β);
b = (r₁ + R) sin30^o + L˙cos(30^o - β);
a = (40 + 220) x 0,866 + 600˙sin 14^o54 =
= 225,16 + 154,278 = 378,438 мм
b = (40 + 200) x 0,5 + 600˙cos 14^o454 =
= 130 + 549,828 = 709,838 мм.From the relation (10) proposed in the claims, we find the value

i

=
β = 15 ^° 6 ′
The coordinates of the rolling axis E of the two-sided lever in a rectangular coordinate system with the origin at point 0 - the centering axis is determined by equations (11), (12)
a = (r ₁ + R) cos30 ^o + L˙sin (30 ^o - β);
b = (r ₁ + R) sin30 ^o + L˙cos (30 ^o - β);
a = (40 + 220) x 0.866 + 600˙sin 14 ^o 54 =
= 225.16 + 154.278 = 378.438 mm
b = (40 + 200) x 0.5 + 600˙cos 14 ^o 454 =
= 130 + 549.828 = 709.838 mm.

The values of the coordinates of the swing axis of the two-roll lever of the centering device, selected as a prototype, with the same technical parameters (r ₁ , r ₂ , R, L) is a = 169.54 mm, b = 727.38 mm.

-

, где P =

;
C =

;
α = arccos

;
A = C˙cos(Ψ- δ) - L cos( φ - δ);
B = C˙sin(Ψ- δ) - L sin( φ - δ);
Ψ = arctg

;
δ = arctg

;
φ = arctg

.The error in centering the proposed and taken as a prototype of the centering devices can be estimated by determining the greatest difference (Δ _max ) of the distances (AO _i , OB _i ) from the centering axis to the centers of the rollers of the two-roller lever according to the following analytical dependence (no conclusion is given):
Δ _max = (OA _i -OB _i ) =

-

where P =

;
C =

;
α = arccos

;
A = C˙cos (Ψ- δ) - L cos (φ - δ);
B = C˙sin (Ψ- δ) - L sin (φ - δ);
Ψ = arctg

;
δ = arctg

;
φ = arctg

.

The above calculations and graphical constructions show that the maximum mixing of the centering axis (Δ _max ) for the design structure of the centering device will be observed with the radii of the centered products equal to r ₁ = 55 mm, r ₁ = 80 mm.

This confirms that, compared with the prototype, the proposed design of the centering device provides higher centering accuracy within a given range (r ₁ = 40 mm, r ₂ = 80 mm) of centered products.

Claims (1)

CENTER OF A TUBE-ROLLING MILL, comprising a housing, two levers mounted in the housing on the swing axes, one of which is equipped with one centering roller, and the other with two centering rollers, synchronizing link articulating the levers, characterized in that the angle β between the straight lines passing through the centers respectively the rollers of the two-roller lever and through the center of the roller closest to the swing axis of this lever and its swing axis are determined from the relation

where r ₁ - the smallest required value of the radius of the centering gauge;
r ₂ - the largest calculated value of the radius of the centering gauge;
R is the radius of the centering roller;
L is the distance from the center of the centering roller closest to the swing axis of the two-roll lever to the swing axis of the lever,
the largest calculated value of the radius of the centering diameter is determined from the relation

where r ₃ - the largest required value of the centering gauge.

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