SU1754243A1 - Method of preparing working rolls for hot rolling operation - Google Patents

Abstract

Use: metal rolling with rolls on wide-strip hot rolling mills. Essence: rolls are rolled by a roller, on the surface of which protrusions are made in a checkerboard pattern with contact pressure 1.5-2.5 times higher than the ultimate strength of the roll material. After that, the surface of the roll is rolled around with a smooth roller in three stages, at the first stage of which the contact pressure is 1.3-1.5 times higher than the tensile strength of the material of the roll, and at each of the following stages, the pressure is reduced by 1.1-1.2 and 1.4-1.5 times, respectively, relative to the pressure at the first, run-in stage with a smooth roller.

Description

The invention relates to rolling production and can be used to prepare rolls for hot strip wide rolling mills.

A known method of preparing for the operation of the work rolls of the hot rolling stand of a hot rolling mill involves installing the kit into the cage and training them in three stages by loading with a constant radial force while rotating, while at the first stage the loading is 0.3-0.35 from nominal rolling force during rotation for (0.5-1.5) -10 loading cycles, and in the second stage loading is 0.2-0.26 of the nominal rolling force during rotation for (0.3-0, 8) 103 loading cycles, and at the third stage loading is 0.1-0 , 15 from the nominal rolling force during rotation for (0.20, 7) 103 loading cycles. This method allows to increase the operational reliability of the rolls by improving the result of the training of physical and mechanical characteristics of the working layer.

However, the field of application of this method is limited to the work rolls of the finishing group of the quarto mill.

Closest to the present invention is a method of preparing work rolls for operation, which includes running their working surface with a roller with a pressure exceeding the strength of the roll material

However, the known method is characterized by a low roll resource due to their insufficient strength in the form that the material of the subsurface layers of the roll is not strengthened.

WITH

The aim of the invention is to increase the resource of the rolls by increasing their strength.

This goal is achieved by rolling the rollers with a roller, on the surface of which rolls are made in a staggered manner, with a contact pressure 1.5-2.5 times greater than the strength of the roll material. After that, the surface of the roll is rolled in a smooth roller in three stages, in the first of which the contact pressure is 1.3–1.5 times higher than the limit of impacted material of the roll, and at each of the subsequent stages it is reduced by 1.1–1.2 and 1.4-1.5 times, respectively, relative to the pressure at the first stage of running with a smooth roller.

The optimality of the proposed method is confirmed by the results of an industrial inspection on the rolls of a hot rolling mill 1450 during operation in a broadening stand.

For four sets of work rolls of steel 60 XN with an initial parameter of 790-795 mm, hardness of 32-34 units, According to Shore and strength of the material on the surface of 790 MPa, before each installation, a run-in was carried out according to the proposed method (three sets) and the known {one set ).

During the run-in, a grooved roller made of steel of the HVG grade with a diameter of 200 mm and a width of 70 mm was used, having protrusions 2 mm high in the form of regular quadrangular truncated pyramids with a base side length of 5 mm and a face tilt angle of 75 °. The protrusions on the roller were arranged in a checkerboard pattern with a distance of 10 mm between the centers. The subsequent run-in was made with a smooth roller made of steel grade HV G with a diameter of 200 mm and a width of 50 mm. During the run-in, engine oil was used as a lubricating fluid.

The contact pressure during rolling of the reef roller was 1185 MPa, which exceeds the strength of the roll material

1.5 times. After that, the rolling of the rolls was carried out with a smooth roller in three stages with the value of the contact pressure at each of the stages respectively 1027 MPa, which in

1.3 times the roll material; 856 MPa, i.e. 1.2 times less than at the first stage of running in with a smooth roller, and 685 MPa, t, e. 1.25 times less than in the previous step. After hardening, the average hardness of the rolls increased to 41 units. by Shore.

According to a known roll test, a roll set was made with a contact pressure of 1250 MPa. Average

The working surface of the rolls after running was 37 units. by Shore.

The use of the proposed method allows an increase in the roll life by at least 1.8 times due to an increase in

strength of the roll by creating a stress-strain state, improve the performance of rolling mills by reducing the frequency of unscheduled transfers by 3-5%.

Claims (1)

Invention Formula The method of preparing hot rolls for operation, including rolling their working surface with a roller with a contact pressure exceeding the tensile strength of the plant material, characterized in that, in order to increase the durability of the rolls by increasing their strength, the surfaces of which are made in a checkerboard pattern with protrusions with a contact pressure 1.5-2.5 times greater than the tensile strength of the roll material, after which the roll surface is rolled in a smooth roller in three steps, in the first of Second, the contact pressure is set e 1.3–1.5 times the tensile strength of the roll material, and in the second and third stages the contact pressure is reduced by 1.1–1.2 and 1.4–1.5 times, respectively, relative to the contact pressure on perzom run-in with a smooth roller,