SU1419774A1 - Method of rolling metal on billet mill - Google Patents

Abstract

The invention can be used in the metallurgical industry on billet rolling mills and squeezing cells of section mills. The purpose of the invention is to increase the resource of the rolls. The hardness and diameter of the cast iron rolls of various grades and hardnesses are measured, the upper roll is set to a smaller diameter of nodular cast iron and with a strength determined by strength 6 (1,06-1,14) 6 -, where 6 and 6n metal strength lia bending of the upper and lower rolls, respectively; Ij, Hz is the diameter of the upper and lower rolls, respectively, and the ratio of its hardness to the hardness of the lower roll is inversely proportional to the ratio of their strengths. 2 tab. (L

Description

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The invention relates to the metallurgical industry and can be used on billet mills and crimping (roughing) cages of section mills.

The aim of the invention is to increase the resource of the rolls.

Before rolling, hardness and roll meters are measured. The upper set roll of nodular cast iron, the strength and hardness of which is determined according to mathematical relationships.

Investigation of the causes of failures of the rolls of billet mills of the mill makes it impossible that the main ones are breakdowns, as well as the discrepancy between the intensity of wear of the upper and lower rolls in the set. As a result, one of the rolls of the set has to be either replaced with a new one in the event of a breakdown, or from the less worn out roll, when it is restored, remove the serviceable working layer in order to ensure that their diameters match. On the basis of experimental laboratory studies and approbation under industrial conditions, dependences were established between the ratio of roll diameters to their strength and hardness. The response function was the life of the set of rolls of the cage, significant factors (diameter, hardness, strength were determined based on a multivariate regression analysis as a result of a passive experiment. On the basis of an active experiment, the ratio of the rolls' strengths was established on the NZS in the ratio of their diameter.

The lower limit of 1.06 is set on the condition of preventing breakages at the lowest possible pressure on the billet mills, taking into account the maintenance of equivalent wear intensity of both rolls of the set. At the same time, wear resistance limits are established and the range of hardness changes between the upper and lower rolls, in which the required reliability of the rolls is achieved due to their strength. Taking into account the same condition (wear resistance), the upper permissible limit (1.14) is also set, the value of which is limited by the stiffness of the roller unit that is acceptable for these types of mills.

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perceiver up to 70% of the total elastic deformation of the cage.

The hardness of the rolls is inversely proportional to their strength to compensate for the loss of the life of the rolls due to the difference in their strength and diameter.

According to the proposed method, the preparation of the stand rolls is carried out as follows.

According to the calibration data, the diameter of the lower roll exceeding the diameter by 6 mm compared with the upper one is determined by measuring the diameter of the lower roll 580 mm and the diameter of the upper roll 574 mm. The roll of the SPHN 48 performance, which ensures the maximum wear resistance of the material in the temperature-deformation speed range of rolling on the NCS and has a bending strength of 450 MPa, is set lower. In this case, with these parameters of the lower roll, there are several sets in which only the parameters of the upper hitch are changed in accordance with the mathematical dependence:

6, (1.06 - 1.14) 6n -

Uh

where eg and bz is the strength of the metal to bend the upper and lower rolls, respectively;

DJ and Bc - diameter of the upper and lower rolls, respectively.

Specific values of the parameters of strength and hardness of the upper roll of the design of the SPRSH are prescribed for the first observation at the lower limit, for the second observation - with the average value, for the third - the upper limit, and also observations are made with the parameters that exceed the suggested range, and this goal is not achieved (table. l). In each case, 10-12 sets of rolls were used for each stand of group 580.

B tab. Figure 1 shows the dependence of the resource utilization ratio on the roll parameters.

The analysis of the given data shows that in the proposed range in

as a result of the increased reliability of the rolls, their life is 100% utilized,

while, due to roll breakages, their life at overshoot of limit values will not exceed 76.3-89.4%.

A comparative analysis of the implementation of the known and proposed methods of Table 2 shows that due to the optimization of the strength and resistance to abrasion of the set of rolls of the stand, the indicators of its work have increased: the development time from 9.48-24.1 thousand tons to 42.3 - 58.0 thousand tons, the number of installations from 4-6 to 7-13, roll life from 56.8-118.0 thousand tons to 326.2-657.3 thousand tons. In addition, when using the proposed method, the cutting of the working layer with each regrinding was reduced by 12.6-17.8%.

In tab. 2 presents data for comparing the effectiveness of the known and proposed methods for preparing the rolls in the stand for operation.

Data analysis table. 2 testifies that with the values of the parameters corresponding to the proposed range, and the values of the strength and hardness of the material and their ratios, the performance of the shaft

ka are almost the same and reach their maximum value, i.e. optimality condition according to statistical data is achieved in the entire proposed range of ratios.

Increasing the life of the rolls by increasing reliability as a result of their rational picking in preparation for operation ensures a reduction in the consumption of rolls by 0.16 kg / ton.

Claims (1)

Invention Formula The method of rolling metal on a billet mill, including compression of the workpiece in cast iron rolls of different 74 diameters and hardness, characterized in that, in order to increase the life of the rolls, the reduction is performed in rolls, the upper of which is made of nodular cast iron with a strength equal to (l, 1,14) Where  n BCI 6c is the bending strength of the material of the upper and lower rolls, respectively; Dj and DU - diameter of the upper and lower P rolls, respectively, while the ratio of the hardness of the materials of the upper and HKJteero rolls is set inversely proportional to the ratio of their strength. Table 1 20 25 thirty Coefficient-Output beyond ent-relation, lower tensile strength of metal-Lower la rolls The average Top Exit for upper limit 1,040,763 1,061.01, 101.0 1.141.0 1.150,894 Table 2 The best way The time for the installation, tewt Number of units, pcs. Resource, thousand tons Known method The operating time for the installation, thousand tons Number of units, pcs Resource, thous. 42.3 - 53.4 46.9 - 58.0 46.6 - 50.5 8-12 9-11 7-- 13 338.4 - 640.8 422.7 - 638, 5 326.2 - 657.3 9.48 - 24.1 4-6 56.8 - 118.0 Note, In the numerator, the bending strength of the material of the roll, MPa; denominator - hardness of the roll barrel, HS. 46.6 - 50.5