RU2030931C1 - Method of adjusting trio screw rolling mill - Google Patents

Abstract

FIELD: working of metal. SUBSTANCE: method involves adjusting pass for effectuating subsequent run by moving upper rolls symmetrically at an acute angle with respect to vertical axis of pass for a value of 0.6-0.9 of required value of reduction in this run. EFFECT: increased efficiency and enhanced reliability of adjusting and precision of adjusting. 2 dwg, 1 tbl

Description

 The invention relates to the processing of metals by pressure, relates to the setting of the mill and can be used on existing and planned screw rolling mills in the production of pipes and rods.

 There is a method of setting up a helical rolling mill, according to which the caliber corresponding to the next pass is set by moving all three rolls of the mill by the same amount equal to half the absolute reduction in this pass [1]. In this case, the rolling axis from passage to passage does not change its position. The rolling process with this setting of the mill is characterized by a significant non-uniformity of deformations along the cross section. The greatest development of plastic deformation is in the peripheral layers of the workpiece, and the central layers of the workpiece do not receive sufficient study. In this case, the constant position of the rolling axis in this case complicates the transition to rolling of various diameters and reduces productivity due to the time spent on adjusting the input and output sides of the mill.

 The closest in technical essence to the invention is the method [2], which includes setting the rolls at the feed and rolling angles and setting the caliber to a predetermined diameter by symmetric movement of the two upper rolls with the lower roll stationary.

 The disadvantage of this method is the asymmetry of the deformation zone, while in the central layers of the workpiece strong tensile stresses develop, leading to the formation of a central fracture of the metal in the axial zone.

 The technical result of the invention is to provide the necessary degree of elaboration of the structure.

 This is achieved by the fact that in the method of setting up a three-roll helical rolling mill with a gauge forming a lower stationary roll and two upper rolls, including setting the rolls at the feed and rolling angles, symmetrical movement of the upper rolls on the caliber, according to the invention, the caliber is set for the next pass by moving the upper rolls per gauge in directions at an acute angle to the vertical axis of the gauge, at which the displacement of each roll is 0.6-0.9 that passage of compression.

 This method of setting the mill rolling helix will provide a rational diagram of the stress-strain state and the necessary degree of study of the structure due to the claimed range of movement of the rolls.

 Figures 1 and 2 show a cross section of the deformation zone in a plane passing through the centers of the rolls.

 Work rolls 1, 2, 3 form a caliber 4 of a given section, equal to the diameter of the workpiece in the section corresponding to the pinch rolls. Work rolls are installed on the feed and rolling corners. The gauge is installed by symmetric movement of the rolls 1 and 2 by the same value S in the directions at an acute angle to the vertical axis of the gauge, and the roll 3 remains stationary (does not move).

 The setting of the mill for a specific caliber by the proposed method can be carried out with the possibility of installing both a symmetric and an asymmetric deformation zone.

 The configuration of the mill with the possibility of the formation of both symmetric and asymmetric caliber is as follows.

The rolls are mounted in such a way that they form a symmetrical caliber. In this case, the axis of the rolls intersect at a central point of a symmetrical caliber at an angle of 120 ^about . Two axes of the mill are moved along these axes with the third permanently fixed.

 The direct relationship between the absolute compression Δ Z and the corresponding value of the movement of the rolls for the case of maintaining a symmetrical caliber in all passes is uniquely determined.

 Show her.

, O

'O₁' = O

'O₁' = 120^o
По теореме косинусов из Δ O₃O_к'O₁':

O₃O₁'

=

O₃O_к'

+

O_к'O₁'

- 2

O₃O_к'

х

O_к'O₁'

^. cos 120^o

O₃O₁'

= (R_b + R_i-1)² + (R_b + R_i-1)² - 2(R_b + +R_i-1) ^. (R_b + R_i-1)

-

O₃O₁'

= 3

R_b + R

O₃O₁'

=

R_b + R

Аналогично из Δ O₃O_кO₁

O₃O

=

(R_b + r_i)
Тогда S_i =

O₃O₁'

-

O₃O

=

(R_i-1 - r_i) или
Si =

Z_i
Для общего случая настройки стана по предлагаемому способу связь величин перемещения валков и обжатия выражена неявно присутствует назначение радиуса валков. Но эту величину можно считать постоянной характеристикой стана винтовой прокатки, поскольку диаметр валков стана винтовой прокатки связан с минимально возможным диаметром калибра соотношением D_b ≈ 6d_кmin (условие свода валков на минимально возможный калибр), а для конкретного типоразмера стана величина минимального калибра d_кmin однозначно определена. Поэтому, именно величины перемещения валков и обжатия являются определяющими для различных способов настройки калибра станов винтовой прокатки.R _b = (O ₃ L) = (O ₁ K) = (O ₁ 'K') - roll radius
r _i = (O _to K) is the radius of the caliber in the i-th passage
R _i-1 = (O _to 'K') - caliber radius in i-1 pass
Δ Z _i = 2 (R _i-1 - r _i ) - the value of the absolute compression per pass
(O _to 'O _to ) =

, O

'O ₁ ' = O

'O ₁ ' = 120 ^o
By the theorem of cosines from Δ O ₃ O _to 'O ₁ ':

O ₃ O ₁ '

=

O ₃ O _to '

+

O _to 'O ₁ '

- 2

O ₃ O _to '

x

O _to 'O ₁ '

^. cos 120 ^o

O ₃ O ₁ '

= (R _b + R _i-1 ) ² + (R _b + R _i-1 ) ² - 2 (R _b + + R _i-1 ) ^. (R _b + R _i-1 )

-

O ₃ O ₁ '

= 3

R _b + R

O ₃ O ₁ '

=

R _b + R

Similarly from Δ O ₃ O _to O ₁

O ₃ O

=

(R _b + r _i )
Then S _i =

O ₃ O ₁ '

-

O ₃ O

=

(R _i-1 - r _i ) or
Si =

Z _i
For the General case, the settings of the mill according to the proposed method, the relationship between the values of the movement of the rolls and compression expressed implicitly there is an appointment radius of the rolls. But this value can be considered a constant characteristic of the screw rolling mill, since the diameter of the rolls of the screw rolling mill is associated with the smallest possible caliber diameter by the ratio D _b ≈ 6d _kmin (condition for roll _reduction to the smallest possible caliber), and for a particular mill size the minimum caliber d _{kmin is} unambiguous defined. Therefore, it is the magnitude of the movement of the rolls and compression that are decisive for various methods of setting the caliber of the helical rolling mills.

Taking into account the actual values of these parameters for the existing and planned helical rolling mills, we obtain that the displacement of each of the two rolls is (0.6 ... 0.9) Δ Z _i . The lower values of the interval should be used when setting up the mill for deformation of materials with the initial cast structure in order to obtain an intensively worked out regulated structure, which is achieved in the asymmetric deformation zone due to the action of powerful shear stresses over the entire section of the roll.

 The setting of the mill in accordance with the upper values of the interval should be made for rolling materials with a pre-worked out or unregulated structure, which will improve the accuracy of the rolled stock in a symmetrical (or close to symmetrical) gauge.

 Example 1. At the RSP-500 mill, two-phase α + β-ingots with a diameter of 500 mm were rolled from W3-1 alloys (with a regulated structure) and a single-phase W1-0 alloy (with an unregulated structure).

The rolls of the RSP-500 mill had a pinch diameter of 600 mm. The rolling process was carried out to obtain a finished bar with a diameter of 100 mm according to the scheme Φ 500 _ → Φ 440 _ → Φ 360 _ → Φ 240 _ → Φ 100. In this case, the mill was adjusted according to the proposed method by symmetric movement of two rolls with a stationary third. The setting of the mill during rolling of the alloy W1-0 (the structure is not regulated) was carried out by moving the rolls by the value of S _i = 0.87 Δ Z _i.
When rolling a W3-1 alloy (the requirements for the structure according to GOST 26492-85 are not higher than the 8th point), the mill was adjusted by moving the rolls in directions at an acute angle to the vertical axis of the gauge by the value S _i = (0.6 ... 0, 9) Δ Z _i . The tuning parameters are given in the table. On the obtained rods, the macrostructure was studied, the accuracy of geometric dimensions was measured. The structure of the bars of the alloy W3-1 was estimated 5.. .6 points, the accuracy of the rods (absolute deviation of the diameter) of the W3-1 alloy was ± 1.8 mm, of the W1-0 alloy ± 0.7 mm (± 3 mm is allowed according to GOST 26492-85).

 For comparison, the rods of these alloys were rolled along the specified route, and the mill was adjusted by moving all three rolls by an amount determined according to the prototype method. The time required to set up the mill in this case increased by 1.5-2.2 times. In this case, the structure of the obtained bars was estimated at 8–9 points. Due to the expansion of the peeling during increased pauses between passes, the accuracy of the resulting rods deteriorated (± 3.5 mm).

 The proposed method of adjusting the mill provides an increase in productivity by reducing the setup time of the mill, makes it possible to control the stress-strain state scheme, which allows you to work out the metal structure over the entire section of the roll, simplifies the tuning operations by moving two rolls by the same amount with a stationary third.

Claims (1)

 METHOD FOR SETTING A THREE-ROLLER SCREW ROLLING MACHINE with a gauge forming a lower stationary roll and two upper rolls, including setting the rolls at the feed and rolling angles and symmetrical movement of the upper rolls to the caliber, characterized in that the caliber is adjusted for the next pass by moving the upper rolls at an acute angle to the vertical axis of the gauge, in which the magnitude of the movement of each roll is 0.6 - 0.9 of the magnitude required in this passage compression.

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