UA35063A - Method of reinforcing surface of forming rolls - Google Patents

Abstract

The invention relates to the rolling production. A method includes preliminary grinding to required diameter, smooth rolling of surface of roll by roller during rotation of the roll around axis in horizontal plane. The smooth rolling of surface of shaft journals is performed by differentiation of the values of plastic deformation depending on the initial hardness of journals.

Description

The invention relates to rolling production, as well as to increasing the operational stability of rolling rolls of continuous wide-bar and other mills.

One of the problems of hot rolling of stock (sheets) on wide-stock mills or on mills with a sequential arrangement of cages is to increase the operational stability of the surface of the support rolls by increasing the wear resistance of their necks.

It is known that in order to increase the reliability of the surface of the support rolls, it is necessary to create compressive stresses in the thin surface layer due to the strengthening rolling of the surface with special devices (P.Y.

Lopukhin et al. Strength of rolling rolls. - Alma-Ata, Nauka, 1984. P. 140, 141). In analogy to the strengthening of the surface of the barrels of the support rolls, it is proposed to prestress them under small loads in training cages or in finishing cages of a continuous mill. This processing method ensures an increase in the hardness of the hardened surface of the roll barrels up to 5 H5ZO. However, this method is not suitable for increasing the hardness of the roll necks, since the stress levels in the contact of the neck with the inner ring of the rolling bearing are insufficient for the formation of compressive stresses that provide the necessary plastic deformation of the metal of the necks. So. the considered method does not provide an increase in the wear resistance of the necks of the support rolls and a differentiated increase in surface hardness along the length of the roll.

The closest to the proposed one is the technical solution, which was considered in the work of V. P. Polukhin and others. (Reliability and durability of cold-rolled rolls. Moscow, metallurgy. 1971, p. 99). In this work, the essence of the technology of strengthening the surface of rolling rolls consists in preliminary grinding (metal samples of the rolls) to the required diameter and processing the surface with a roller while rotating the roll around an axis in a horizontal plane. As a result of this treatment, the surface hardness of 9X grade steel samples increases by 2.3-3.4 times compared to untreated samples. The operational stability of the rolls of the twenty-roll mill with such processing increases by 1.3-3 times.

The disadvantage of the considered method is that it lacks the technology of running-in (plastic deformation) of the necks of the support rolls without prior induction heating of the surface layers of the rolls, and the method does not provide a differentiated increase in surface hardness along the length of the roll.

The task of the invention is to improve the method of strengthening the surface of rolling rolls by optimizing the process of running-in (plastic deformation) of their surface.

The technical result of the invention is a differentiated increase in surface hardness and a decrease in the roughness of the necks. at the same time, increasing the wear resistance of the surface of the necks, increasing the service life of the rolls and reducing their costs.

The solution to the problem is provided by the fact that the following differences are provided in the method, which includes preliminary grinding to the required diameter and running-in of the surface of the roll with a roller when rotating the roll around an axis in the horizontal plane: running-in of the surface of the necks of the roll is performed by differentiating the amount of plastic deformation depending on the initial hardness of the necks, at the same time, the crimp value is found by the expression

Ap; , 45 I be dB 700055 lu () where AP - absolute plastic crimping of the neck in diameter (mm);

H5BO - hardness of the surface of the neck according to Shore (initial).

Between essential differences of invention and technical. the result achieved is cause-and-effect relationship. Increasing the crimping of the surface of the neck with lower hardness provides an increase in its hardness to the hardness of the surface of the other neck and, at the same time, increases the service life of the rolls and reduces their costs.

It is known from the practice of the hot rolling mill 1680 of the "Zaporizhstal" steel mill that the support rolls supplied to the steel mill have different surface hardness of the left and right necks.

Measurements show that the absolute hardness of the necks of one specific support roll is 33-45 H5ОЮ, the difference is - 3095.

The presence of such a difference determines the different degree of wear of the necks during operation. It was found that under the same operating conditions, a neck with a lower hardness wears out in one service campaign by 0.4-0.6 mm, while a harder neck receives wear in the range of 0.1-0.2 mm. After pulling the rolls out of the cage, the barrel and neck are polished. At the same time, the diameter of the roll necks before the next installation in the cage is aligned to the smaller worn diameter, which leads to non-productive consumption of neck metal and reduces the service life of the support rolls due to wear (permitted diameter reduction) of the necks with the permitted diameter of the roll barrels.

In fig. shows the scheme of the installation for the implementation of the method of strengthening the necks of the roll, which is proposed. In fig. shown: roll 1 with necks 2, installed in the centers of a lathe type TA826; guides 4, along which the caliper 5 moves, which has a manual control 6, as well as the electric actuator for moving the caliper, which is located under the caliper (not shown in the drawing, because the design serial machine is known); carriage 7 is placed on the caliper, which moves perpendicularly along the longitudinal axis of the roll; a holder 8 with a running-in roller 9 with a diameter of 120 mm and a width of 16 mm is installed in the carriage clamps (NAS - 65-67).

The movement of the carriage 7 is carried out by a manual drive 10, and the amount of movement is controlled by a device 11 with a calibrated metric scale with a division price of 0.01 mm (by crimping).

This method is implemented as follows. First of all, the worn rolls, which are cut from the cage, are subjected to grinding of the barrel and neck. At the same time, worn necks of different sizes are ground to one diameter, which is set 0.1-0.2 mm less than the diameter of the neck with a smaller diameter. Removal of the working layer of the second neck, which received less wear. correspondingly more by the size of the difference in the diameters of the worn necks. After grinding, the surface roughness of the barrel and roll necks is 1.2-1.8 μm Na. After preparing the necks, measure the hardness of their surface with a standard portable device with the Shore scale (NBZO) and then, using expression (1), determine the values of the absolute crimp for each neck to obtain a surface hardness of less than C 45

NGO The maximum value of the neck hardness of 45 N5BZO is due to the optimal ratio between the hardness of the neck and the inner ring of the rolling bearing with conical rollers, the hardness of which is - 70

H5BO, and the hardness ratio is C - 45/70 5 0.65.

Run-in of the neck with roller 9 is performed as follows. In the initial position, the roller 9 is out of contact with the neck, and with the help of the drive of the carriage 10, the roller is set in the Position to obtain the crimping of the neck along the diameter. After that, the electric rotation drives are turned on. roll and moving caliper 5 along the neck of the roll. At the same time, the speeds of the roll and the caliper are set to ensure a uniform tonality of the surface of the neck without imprints of a narrow roller. Run-in is performed in one pass. In the same way, the second neck is also run-in with the required relative compression of the DP/NZO (see Expression (1)1.

Experiments on checking the proposed wine. stroke is made on the support rolls of the continuous wide-barrel mill 1680 of the "Zaporizhstal" metallurgical plant. The support rolls have a barrel diameter of Ю-1170-1240 mm, a neck diameter of Х-647-650 mm. the length is 710 mm, the material of the rolls is 9ХФ grade steel. the rotation speed of the roll is 9-10 rpm, the speed of the longitudinal feed of the caliper together with the roller with a hardness of NKS 65-67 U-18-20 mm/min.

Experimental data on strengthening the necks of support rolls with a running-in roller are presented in the table. 1. As follows from the table. 1 left (neck 1) and right (neck 2) in all cases had different surface hardness and in order to obtain the permissible hardness У 45 Н5О (see above) with the initial hardness of the necks « 45 Н5БЗО it is necessary to use different crimps. Yes, if the left cervix (Mo 1) has an initial hardness of 33.0-37.2 H5BO (experiments 4, 5, 6). it is necessary to apply crimps in the range of Ap - 0.04-0.06 mm (Ap/Нneo - 10.8-18.2). If the right cervix (Me 2) has an initial hardness of 40.1-41.1 H5BO (experiments 2, 3, 7), it is necessary to apply crimps in the range of Ap - 0.02-0.03 tt (Ap/Нneo - 4.9- 7.5). The processing of the experimental material showed that the optimal value of Ap for obtaining the optimal hardness of the surface of the necks - (45-46) H5O can be obtained from expression (1). So, if the left neck (Me 1) has a surface hardness of 34 H5O, and the right neck (Mo 2) has a surface hardness of 40 H5O, then the optimal crimps from expression (1) should be: left - 0.055 mm, and right - 0.024 mm.

When crimps are less than optimal, according to expression (1). for each specific hardness of the neck, the equality of the hardness of the necks is not ensured, and accordingly there will be a different degree of their wear.

The method of plastic processing of rolling mill roll necks, which is proposed, eliminates the difference in hardness of the left and right roll necks and ensures an increase in their wear resistance and a reduction in the consumption of rolls

Experimental data on determining the optimal crimping of the surface layer of the necks of the support rolls hardness of NBYUO hardness of HVO before running-in after before running-in | after break-in break-in 1 0.01 2.83 35.3 36.4 0.01 2.43 2 42.5 2 0.02 5.9 34.0 38.4 9.02 50 40.5 44.9

From 0.03 9.0 33.3 40.3 0.03 7.5 40.1 45.3 4 0.04 10.8 372 45.4 0.04 9.8 40.8 47.8 0, 05 14.8 33.8 44.6 0.01 2.22 44.2 46.3 6 0.06 18.2 33.0 45.3 0.05 12.7 39.3 49.3 7 0.07 20 ,7 33.7 4v2 0.02 4.9 411 45.6 2 -- o From 3 others; - sh int 6 and 7 7

Claims (1)

The method of strengthening the surface of rolling rolls, which includes preliminary grinding to the required diameter, running-in of the surface of the roll with a roller while rotating the roll around an axis in the horizontal plane, differs in that the running-in of the surface of the roll necks is performed by differentiating the amount of plastic deformation depending on the initial hardness of the necks, while the amount the crimp is installed according to the expression dp 45 biv 7005 (dev 7 where AP - absolute plastic crimp of the neck in diameter (mm); H5BO - hardness of the surface of the neck according to Shore (initial).