SU820943A1 - Method of cooling rolling roll passes - Google Patents

Description

one

The invention relates to ferrous metallurgy, in particular to rolling production and can be used on crimping, billet, large, medium and small-section mills;

A known method of cooling the mill rolls includes the supply of a coolant tangentially to the surface of the rolls on the output side of the metal from the deformation zone 1.

The disadvantages of this method are the uniform distribution of the cooler over the entire roll surface, which cannot provide a uniform temperature field along the length of the barrel (for sheet mills), which contributes to the occurrence of significant thermal stresses leading to increased wear and breakage of the rolls. In addition, this method is characterized by insufficient cooling intensity, since the cooling surface of the roll, to which the chiller is directly supplied, is very small.

The closest in technical essence and the achieved result to the proposed method is the cooling of the calibers of the rolls, which includes the supply of an cooler around the perimeter of the gauge, with a cooler 3-5 times more than in the areas of maximum wear. Minimum wear areas 2.

The disadvantages of this method are that it is impossible to distribute the cooler according to the roll wear, since it is impossible to determine in advance the areas of maximum roll production around the perimeter of the gauge, which does not eliminate the uneven wear, and during the rolling process the control of the coolant supply is difficult. In addition, the service life is reduced.

5 rolls, and a large wear gauges often occurs in areas of the processing part of the rolled section, having a lower temperature. With

This results in a significant specific pressure, leading to an increase in roll wear. The increase in water consumption at these sites leads to a further decrease in the temperature of the metal due to the fact that the cooling water, reflecting from the surface of the gauge, FULLY falls on the rolled strip.

The purpose of the invention is to increase the service life of the rolls. This goal is achieved by the fact that in the method involving the supply of coolant around the perimeter of the gauge, the cooler is supplied in proportion to the amount of slip between the metal and 8lkg1mi, and the ratio between the densities of the cooler supplied to the areas of maximum and minimum slip is 6-1. flows transferred to the rolls are gliding between the metal and the rolls along the gripping arc, heat transfer when the rolls contact the metal, from the heat load of heat from the metal surface to the rolls, those the floating gap due to the plastic deformation of the metal (ignored during hot rolling). . However, the heat flux arising from sliding between the metal and the rolls constitutes the major share of the thermal loads on the work rolls. For the Zaporozhstal plant sheet mill 1680, the heat loads on the work rolls were determined from the mill finishing group. The results of the determination are given in table. 1. Table 1 a work rolls, x Yu

From the table it can be seen that the heat flux from slip is 80.5-90.5% of the total heat flux. Therefore, the scaling value is a determining factor influencing the thermal loads of the mill rolls. In the roll mill calibers, the slip distribution around the gauge perimeter is uneven. Therefore, the distribution of the cooler around the perimeter of the gauge of the rolling rolls in proportion to the amount of slip allows to obtain a uniform temperature field in the surface layers of the roll. Studies have shown that it is the slip rate, not the rolling speed, which is a direct characteristic of the conditions of roll friction and wear. The coefficient of friction and the temperature gradient depend not on the absolute speed of movement of the bodies, in particular, on the speed of the rolls (or the speed of the metal), but on their relative displacement ipocTH, i.e. slip.

Slip value Average slip speed 0.06 0.25 0.20

Table 2 FIG. 1 shows a stream of caliber; in fig. 2 - brook of rhombic caliber. In order to substantiate the optimal values of the flow rate of the cooler, we showed in Blooming 3 of the Krivorozhstal plant investigating the influence of the distribution of the cooler around the gauge on the roll wear. The cooler was supplied in proportion to the amount of slip around the caliber perimeter. According to the calibration of the blooming rolls, the speed mode of its operation and the reduction schemes, the average sliding speeds of the rolled metal relative to the roll surface along the gripping arc were determined. Roll wear was measured using templates and at corresponding points along the creek perimeter (Fig. 1). In tab. Figure 2 shows the amount of slip along the points located along the creek perimeter. At these points, the average slip speeds are determined, the density of the coolant is distributed, and the roll wear is measured. 0.17 0.08 0.07 0.05

In tab. 3 shows the density of the cooling water supplied by

From tab. 3 it follows that when the ratios between the density of cooling water supplied to the areas of maximum and minimum slip are equal to 3.4 and 4.2, both the magnitude and the distribution of wear along the perimeter of the stream; not substantially different. The uneven distribution of wear along the perimeter of the brook is 4.5 times. With ratios of 5.5; 7.2; 9.3; 11.0 and 14.0, a significant decrease in the amount of wear along the entire perimeter of the stream is observed, and the non-uniformity of wear is reduced by 1.852, 0 times. A further increase in this ratio to 16.8 does not lead to a decrease in the amount of wear, and its unevenness remains the same. Thus, the optimum values of the ratio between the density of the cooler along the perimeter of the stream should be 6–15.

the perimeter of the stream and the amount of wear of the roll at the points indicated on the caliber.

Table 3

Example. Conducted a test of the proposed method at the mill 730 (in cage 8) of the Krivorozhstal plant. The slip value is determined by the points of the brook of the rhombic caliber (Fig. 2), water is distributed and the gauge wear is measured. The ratio between the density of cooling water supplied to the maximum areas (points 2–4 and 8–10). and the minimum slip (points 1 and 11) is 9.5. After rolling 80050 tons of metal in this gauge, the wear of the working gauge is measured using templates. In tab. 4 shows the wear values of the working gauge layer by 11 points. From tab. 4, it follows that when using the proposed method, the amount of wear is almost 2 times reduced as compared with the limestone method. The uniform distribution of wear around the perimeter of the gauge with use of the proposed method is increased by 25%. Amount and distribution of wear and tear Wear 2.9 3.5 3.9 4.1 4. 4. 5.0 4.6

Points 1

Proposed Wear 2.1 2.4 2.6 2.8 2.9 3.1 2.9

The proposed method makes it possible to significantly increase the service life of the rolls by reducing the amount of wear and uniformly distributing it around the perimeter of the gauge.

Claims (2)

Invention Formula The method of cooling the gauge rolls, including the supply of a cooler around the perimeter of the gauge, characterized in that, in order to increase the service life of the shaft 10 11 eight The cooler is supplied in proportion to the amount of slip between the metal and the rollers, and the ratio between the densities of the cooler supplied to the maximum and minimum slip areas is 6-15. Sources of information taken into account in the examination 1. USSR author's certificate 410015, cl. B 21 B 27/06, 1974. 2. USSR author's certificate No. 564897, cl. B 21 B 27/06, 1977. Table perimeter caliber 4.0 3.2 3.0 2.8 2.7 2.6 2.4 2.0