RU2492948C1 - Method of operating sheet-rolling mill rolls - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metallurgy and can be used in rolling at sheet-rolling mills and planishing mills with working rolls with different in body diameter and individual and common drives. Proposed method comprises grinding of rolls and grooving of their bodies. Note here that roll surface denting of smaller-diameter body to surface roughness exceeding that of larger-diameter roll while smaller-diameter roll roughness is defined by the formula $$R_{а}(s)=k\cdot \frac{D_L}{D_S}\cdot R_{а}(l):$$

where R_a(s), R_a(l) is smaller- and larger-diameter roll body roughness, mcm ; D_S, D_L are roll body smaller- and larger-diameters, mm; k=2÷4 is coefficient of proportionality.

EFFECT: ruled out additional grinding, lower costs and labor input.

1 tbl, 1 ex

Description

The invention relates to rolling production and can be used in relation to the work rolls of sheet-rolling and training stands with individual and group drive rolls.

There is a method of operating rolls of a sheet rolling mill, including grinding them using abrasive wheels, a shot blasting notch of the barrel surfaces and the subsequent operation of a pair of rolls in a mill [1].

The disadvantage of this method is that the rolls in the pair during grinding must be adjusted to the diameter of the barrels. This increases the consumption of rolls.

The closest analogue to the present invention is a method of operating rolls of a sheet rolling mill, comprising grinding the roll barrels with an abrasive wheel, their subsequent electroerosive notch to obtain a predetermined roughness value R _a, and the work of the roll paired with another roll in the rolling mill stand of 1700 mill [2].

The disadvantage of this method is as follows. The rolls working in the cage, forming a pair, receive various damages (uneven wear, cuts, fat). Therefore, after grinding, until the damage is completely eliminated, the rolls acquire a different barrel diameter. In order to exclude uneven loading in the drive line of the rolls and the bending of the front ends of the rolled strips at the exit of the stand, the large-diameter roll is additionally ground after damage is removed, fitting it in diameter to a twin roll. Diameter adjustment of the rolls leads to an increase in roll consumption.

The technical problem solved by the invention is to reduce the consumption of rolls.

To solve the technical problem in the known method of operating rolls of a sheet rolling mill, including grinding, notching the surfaces of the barrels and the subsequent work of a pair of rolls in the stand, according to the invention, a roll with a smaller diameter of the barrel is incised to a roughness exceeding the roughness of the pair roll, while the ratio of the roughness of the rolls with smaller and larger diameters support equal:

$$R_{\mathrm{but}}(m)=k\cdot \frac{D_B}{D_M}\cdot R_{\mathrm{but}}(b),$$

where R _a (m), R _a (b) is the roughness of the barrel rolls of smaller and larger diameters, microns R _a ;

D _M , D _B - the diameters of the barrels of rolls of smaller and larger diameters, mm;

k = 2 ÷ 4 is the coefficient of proportionality.

The invention consists in the following. The use of rolls with different barrel diameters in the cage leads to an uneven load on the roll drive line: the rolling moment on a roll of a larger diameter increases and decreases on a roll of a smaller diameter. This is unacceptable, as it negatively affects the operating conditions of the drive. In addition, the bending of the front ends of the strips at the exit from the stand with rolls with different barrel diameters complicates their task in the subsequent stand and winder.

A notch of a roll of a smaller diameter to a roughness exceeding the roughness of a pair of rolls allows, due to an increase in the coefficient of friction, to compensate for the asymmetry of rolling due to the difference in diameters in the pair of rolls. This leads to equalization of the load on the line of the main roll drive. At the same time, an increase in lead on the roll with a higher surface roughness reduces the bending of the front ends of the strips.

. Указанное соотношение получено для валков с номинальным диаметром бочек 400-600 мм.The most complete compensation of the asymmetry of deformation due to the difference in diameters in the pair of rolls by the asymmetry of the roughness of their barrels, as shown by experiments, is achieved when the relation $$R_{\mathrm{but}}(m)=k\cdot \frac{D_B}{D_M}\cdot R_{\mathrm{but}}(b)$$

. The indicated ratio was obtained for rolls with a nominal barrel diameter of 400-600 mm.

It was experimentally established that when k is less than 2, compensation of the difference in the diameter of the rolls is not achieved: the load on the drive line of the roll with a large diameter remains higher than on the drive line of a pair of rolls with it. In the case where k exceeds 4, there is overcompensation: the load on the drive line of the roll with a larger diameter becomes lower than on the drive line of the roll with a smaller diameter. In both cases, the contact slip of the metal on the surface of the rolls increases and their wear increases.

Method implementation examples

A pair of work rolls of the quarto 1700 cold rolling mill is subjected to grinding with an abrasive wheel until the traces of wear and accumulated damage are completely removed. After grinding, the diameter of the barrel of the upper roll was D _M = 500 mm, the diameter of the barrel of the lower roll was D _B = 490 mm.

The polished work rolls are notched, which makes it possible to better keep the strip on the rolling line and to exclude the welding of coil turns during subsequent recrystallization annealing.

A barrel of the upper work roll with a large diameter D _{B is} incised using electric-discharge texturing to a roughness of R _a (b) = 1.80 μm. The barrel of the lower work roll of a smaller diameter D _{M is} incised to a roughness R _a (m) exceeding the roughness R _a (b) of the upper roll paired with it, and component:

$$R_{\mathrm{but}}(m)=k\cdot \frac{D_B}{D_M}\cdot R_{\mathrm{but}}(b)=3\cdot \frac{500}{490}\cdot 1.80=5.51m\mathrm{to}m.$$

A pair of notched rolls is dumped into the 4th stand of a continuous mill with an individual electric drive of the work rolls and cold rolling of strips with a cross section of 0.7 × 1500 mm from 08ps steel is carried out.

Due to the fact that the lower work roll with a smaller barrel diameter has a roughness of R _a (m) = 5.51 μm, exceeding the roughness of the barrel of the upper roll R _a (b) = 1.80 μm, the front ends of the strips leave the cage without bending, and drive moments on the upper M _in and lower M _n working rolls are equal and are: M _in = M _n = 2.4 t · m The use of the upper and lower work rolls without additional grinding in order to align the diameters of their barrels reduces the specific consumption of rolls to q = 1.2 kg / t (kilograms of discarded rolls per ton of rolled products). The uniform load at the time of rolling the drive lines of the upper and lower work rolls extends the life of the mechanical equipment.

Implementation options of the proposed method and indicators of their effectiveness are presented in the table.

Table Modes of operation of the rolls and their effectiveness No. Bending front ends q options k M _in / M _n kg / t one 5 0.65 presence. 3.3 2 2 1,0 absent. 1,2 3 3 1,0 absent. 1,2 four four 1,0 absent. 1,2 5 one 1.35 presence. 3.2 6 [2] - 1,0 absent. 3.3

From the data presented in the table, it follows that in the case of the implementation of the proposed method (options No. 2-4), a reduction in the flow rate of rolls is achieved with a uniform load at the time of rolling the main drive line, bending of the front ends of the strips at the exit of the stand does not occur. In the case of exorbitant values of k (options No. 1 and No. 5), the flow rate of the rolls and the uneven load of the main drive increase, there is a bend of the front ends of the strips. When implementing the closest analogue [2] with additional grinding of a roll of a larger diameter to the diameter of a twin roll with it (option 6), the flow rate of the rolls also increases.

, позволяет исключить необходимость дополнительного шлифования валка с большим диаметром, уменьшить трудозатраты на шлифование, сократить расход валков.The technical and economic advantages of the proposed method consist in that the notch of the roll with a smaller diameter to a roughness greater than that of a roll with a large diameter, as well as the fulfillment of the proposed ratio of the roughness of the rolls $$R_{\mathrm{but}}(m)=k\cdot \frac{D_B}{D_M}\cdot R_{\mathrm{but}}(b)$$

, eliminates the need for additional grinding of the roll with a large diameter, reduce labor costs for grinding, reduce the consumption of rolls.

In the process of testing the proposed method, a side positive effect was found, which was expressed in a reduction in energy consumption for rolling in stands with rolls of unequal diameter and roughness of their barrels by 10-12%.

The closest analogue was adopted as the base object. Using the proposed method will increase the profitability of the production of cold rolled sheet metal by 3-5%.

Literary sources used in the preparation of the description of the invention:

1. L.I. Borovik, A.I. Dobronravov "Technology for the preparation and operation of rolls of sheet mills" M. Metallurgy, 1984 p.50-55.

2. RF patent No. 2187393, IPC B21B 28/02, 2002

Claims (1)

A method of rolling strips in a sheet rolling mill, including the use in roll stands with various diameters of drums subjected to grinding, notching their surfaces, characterized in that the notching of the roll surface with a smaller barrel diameter is carried out to a roughness exceeding the surface roughness of a pair roll with a large diameter, when this roughness of the roll with a smaller diameter is determined from the condition:
$$R_{\mathrm{but}}(m)=k\cdot \frac{D_B}{D_M}\cdot R_{\mathrm{but}}(b),$$

where R _a (m), R _a (b) is the roughness of the barrel rolls of smaller and larger diameters, microns;
D _M , D _B - the diameters of the barrels of rolls of smaller and larger diameters, respectively, mm;
k = 2 ÷ 4 - coefficient of proportionality.