RU50443U1 - CRICKING A TRIO OF THICKBOARD MILL - Google Patents

Abstract

The invention relates to the processing of metals by pressure, in particular, to a tool (rolls) for hot rolling of thick sheets. The main goal solved by the utility model is to reduce production costs by reducing rolled waste and increasing the wear resistance of the rolls. The proposed trio stand contains upper, lower and middle rolls with barrels of predetermined diameters and is characterized in that for rolling sheets with a thickness h≤8 mm, the ratio D _H / D _B = 1,0003 ... 1,0009, and for rolling sheets with a thickness with h> 8 mm - D _B / D _H = 1,0003 ... 1,0009, where D _B and D _H are the diameters of the barrels of the upper and lower rolls, respectively, and the hardness of the barrel of the middle roll in all cases by 3. ..5% less hardness of the barrels of the said rolls.

Description

The utility model relates to rolling production and can be used in the manufacture of thick hot-rolled sheets.

Such sheets are usually rolled on two-stand mills, one of the stands of which contains three rolls, and the middle of them is of smaller diameter (stand of the Laut trio). The barrels of these rolls are made with surfaces of different hardness. Design features of the mentioned stands and their rolls are described in sufficient detail, for example, in the book of P.I. Polukhina et al. “Rolling production”, M., Metallurgizdat, I960, p. 591-592.

Known stand quarto sheet rolling mill, a feature of which are backup rolls sectioned along the length of the barrel. Between smooth short roller sections, intermediate bearing bearings are located, with the help of which, the anti-bending force of the work rolls is regulated (see Japanese Pat. No. 50-32076, class B21B 29/00, publ. 17.10.75). A cage of this design is not acceptable for rolling thick sheets at Laut's mill.

The closest analogue to the claimed object is a three-roll stand (trio stand) of the Laut mill, described in the book by PI, Polukhin and others “Rolling production”, 3rd ed., M., “Metallurgy”, 1982, p. 357-359.

This cage contains the upper, lower and middle rolls of different diameters of their barrels and is characterized by the fact that the diameter of the barrel of the middle roll is 2.4 ... 3.5 times less than that of the upper and lower rolls, and the barrel length is larger than 2.5 ... 3.0 times.

The disadvantages of the stand of this design are the uncertainty in the ratio of the diameters of the upper and lower rolls, as well as the hardness of all

rolls, which increases the output of substandard thick sheets and reduces the tool life.

The technical task of the proposed utility model is to reduce production costs by reducing rolled waste and increasing the wear resistance of the rolls.

To solve this problem, in the stand of a trio of a plate mill containing upper, lower and middle rolls with barrels of given diameters, when rolling sheets with a thickness of h≤8 mm, the ratio D _H / D _B = 1,0003 ... 1,0009, and when rolling sheets with h> 8 mm - D _B / D _H = 1,0003 ... 1,0009, where D _B and D _H are the diameters of the barrels of the upper and lower rolls, respectively, and the hardness of the barrel of the middle roll is 3 .. .5% less hardness of the drums of said rolls.

The essence of the claimed technical solution consists, firstly, in changing the ratio of the diameters of the barrels of the upper and lower rolls depending on the thickness of the rolled sheets, and, in one case, the diameter of the lower roll is larger, and in the other, the diameter of the upper roll. Secondly, the hardness of the barrel of the middle roll is made a certain amount less than the hardness of the other two rolls. As a result of this, as shown by experiments (see below), the wear resistance of the rolls is increased, and cases of bending of the head of the rolled sheet and its jam are excluded, which reduces metal waste.

The proposed trio stand (its rolls) is shown schematically in FIG.

Upper 1, lower 2 and middle 3 rolls containing drums 4 with diameters, respectively, D _B , D _H and d and trunnion 5 placed in the pillow bearings are installed in the stand beds in pillow bearings (not shown in FIG. 1) not shown). The value of the ratio D _B / D _H depends on the thickness of the rolled sheets, and the hardness of the barrel roll 3 is always less than the hardness of the barrel rolls 1 and 2.

Experimental verification of the proposed facility was carried out on a plate mill 2350 OJSC "Magnitogorsk Iron and Steel Works".

To this end, during hot rolling of sheets with a thickness of 6 ... 30 mm from steels of various grades, the ratio of the diameters of the upper and lower rolls of the trio stand of this mill, as well as the hardness of the roll barrels, were evaluated, evaluating the results on the quality of the rolled products and the duration of the work roll campaign (before transshipment any of them for wear).

The best results (non-standard yield within 0.1 ... 0.3% at the maximum duration of the rolls) were obtained with the implementation of the claimed technical solution. Deviation from the above optimal ratios worsened the achieved indicators.

So, when rolling sheets with h≤8 mm with a larger value of D _B and with D _B = D _{H, the} output of substandard increased, respectively, to 1.6 and 1.2%, and the duration of the campaign of the upper and lower rolls (compared to the maximum achieved) decreased by 1.3 ... 1.2 times. Similar results for sheets with h> 8 mm were obtained for D _B = D _H and D _B <D _H.

With the hardness of the barrel of the average roll of lower hardness of the other two rolls by 6 ... 9%, the duration of its campaign decreased, on average, by 1.4 times, and with the indicated difference in the range of 0 ... 2%, accelerated wear of the upper and lower rolls , which forced them to premature transshipment.

Comparative tests of a known object, taken as the closest analogue, were not carried out due to the uncertainty of the values of the ratio of hardness and roll diameters.

Thus, an experimental verification confirmed the acceptability of the technical solution found to achieve the goal and its advantage over a known object.

The feasibility study showed that the use of the proposed utility model in the production of thick hot-rolled

sheets reduces production costs by an average of 8% by reducing rolled waste and increasing the wear resistance of rolls.

Concrete example

1. In a stand of a trio of a plate mill with a diameter of the upper roll of 950 mm, a sheet 6 mm thick is rolled.

The diameter of the lower roll: D _H = D _B × 1,0006 = 950 × 1,0006≈950.6 mm; the diameter of the top is 950 mm.

The hardness of the barrels of the upper and lower rolls - 68 units. along Shore, the average roll - 68 × 0.97≈66 units.

2. Rolling sheets with a thickness of 20 mm in the same stand. The diameter of the lower roll is 950 mm, the diameter of the upper roll is D _B = D _H × 1,0005 = 950 × 1,0005≈950.5 mm.

The hardness of the barrels of the upper and lower rolls - 68 units. Shore, the average roll - 68 × 0.95≈65 units.

Claims (1)

A crate of a trio of a plate mill for rolling sheets of predetermined thicknesses, comprising upper, lower and middle rolls with barrels of predetermined diameters, characterized in that for rolling sheets of thickness h≤8 mm, the ratio D _H / D _B = 1,0003 ... 1, 0009, and for rolling sheets with a thickness of h> 8 mm - D _B / D _H = 1,0003 ... 1,0009, where D _B and D _H are the diameters of the barrels of the upper and lower rolls, respectively, and the hardness of the barrel is medium the roll in all cases is 3 ... 5% less than the hardness of the barrels of the said rolls.