RU50444U1 - CRICKING A TRIO OF THICKBOARD MILL - Google Patents

Abstract

The invention relates to the processing of metals by pressure, in particular, to equipment for hot rolling of thick sheets. The main goal solved by the utility model is to reduce labor costs by improving the quality of hire and extending the work rolls campaign. The proposed trio stand contains upper, lower and middle rolls with a given configuration of their barrels and is characterized in that at the beginning of the working campaign, the barrels of the upper and lower rolls are made with a convex circular surface forming them having a maximum convexity δ in the middle of the barrel length, and forming a barrel surface middle roll equidistant by said generator, wherein the absolute value δ is _a middle roll values δ, modifying its barrel surface, the extent of wear of barrels of the upper and lower rollers from the concave to MY kloy and _with extreme values δ are within ± 0,003R, where R - radius of the middle roll barrels.

Description

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

Plate steel is most often rolled on two-stand mills, one of the stands of which contains three rolls and the middle of them has the smallest diameter. The barrels forming these rolls are curvilinear; moreover, the barrels can be either convex or concave. The designs of the existing trio stands and the peculiarities of their rolls are described in sufficient detail, for example, in the book by P. I. Polukhin and others. “Rolling production”, M., Metallurgizdat, 1960, pp. 591-592.

A known rolling stand containing work rolls installed in pillow supports is provided with protrusions which during operation engage and fix the position of the pillows, and during transshipment are bred by lifting the upper roll (see US Pat. RF No. 1602145, C. B 21 V 31/10, publ. 06.12.73). However, this stand is not suitable for rolling thick sheets.

The closest analogue to the claimed object is a three-roll mill stand of Laut, described in the book of P.I. Polukhin and others. "Rolling production", 3rd ed., M., "Metallurgy", 1982, S. 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 disadvantage of this stand design is the uncertainty of the configuration of the roll barrels, which increases the labor costs when using them to obtain high-quality rolled products at maximum

wear resistance of the rolls, providing the required duration of the working campaign of the tool.

The technical task of the proposed utility model is to reduce labor costs by improving the quality of hire and extending the work rolls campaign.

To solve this problem, in the stand of a trio of a plate mill containing upper, lower and middle rolls with a given configuration of their barrels, at the beginning of the working campaign, the barrels of the upper and lower rolls are made with a convex circular surface forming them having a maximum convexity δ in the middle of the barrel length, and forming the surface of the roll barrels medium equidistant by said generator, wherein the absolute value δ is _a middle roll values δ, modifying its barrel surface, the extent of wear of barrels of the upper and lower rolls of concave to convex, and _{with the} extreme values δ are within ± 0,003R, where R - radius of the middle roll barrels.

The essence of the proposed technical solution is to choose the optimal (to achieve the goal) configuration and hardness of the roll barrels of the trio stand. In this case, the configuration (δ value) on the upper and lower rolls is a mirror image of the configuration of the middle roll barrel, and as the upper and lower rolls wear, when the convex generatrix becomes straightforward and then concave, the shape of the middle barrel roll. But at any moment, the roll gap remains practically constant, i.e. the curves of the generators are equidistant. As a result of this, as shown by experiments (see below), the maximum duration of the working campaign of the rolls is achieved with high quality rolled thick sheets.

The proposed trio stand is shown schematically in FIG.

This cage contains the upper and lower rolls 1 and the middle roll 2 with the radius of the barrel R, the trunnions 3 of which are installed in pillows-supports (not

shown) placed in the beds. The barrels forming 4 rolls are made along an arc of a circle, while if this rolls 1 (at the beginning of the campaign) is convex with a maximum arrow δ, then it is concave on roll 2, and the specified roll gap Δ remains constant all the time. The length of the roll barrels - L.

As the barrels of rolls 1 wear out, their generatrix from convex passes to concave (shown by a dotted line), and the generatrix of roll 2 passes from concave to convex, and the maximum value of the arrow of the arcuate forming barrel of this roll is δ _с = ± 0.003R.

Since the average roll 2 is reloaded (by wear) much more often than the upper and lower rolls 1, then as their barrels wear out (with a change in the value of δ), the value of δ _{from the} middle roll is taken when sanding its barrel so that the gap Δ is equal to the entire length of L.

A pilot test of the proposed technical solution was carried out on a plate mill 2350 OJSC "Magnitogorsk Iron and Steel Works".

For this purpose, when rolling plate steel of various assortments, the configuration of all the rolls of the trio stand of this mill was varied (the diameter of the barrels of the upper and lower rolls is 950 mm, the average is 550 mm), changing not only the convexity (concavity), but also the character of the forming barrels (parabolic or circular), as well as using a set of rolls with a variable roll gap.

The best results: the output of 1st grade rolled products within 99.5 ... 99.8% with maximum wear resistance (duration of the working campaign) of the rolls obtained during the implementation of the proposed facility. Deviations from the recommended parameters of the roll barrels worsened the results.

For example, a change in the size of the roll gaps along the length of the roll barrels (i.e. violation of the equidistance of their generators) reduced the output of the first grade to 87 ... 92%, and the duration of the work campaign of the rolls, on average,

1.3 times. Similar results were also achieved by a decrease in δ _s (on the average roll) to 0 ... 0.002R (convexity at the beginning of its operation), and at δ _c > 0.003R, microcracks were observed on the barrel of the average roll, forcing premature transshipment (replacement this roll).

With too much concavity of the middle roll (-0.006R ...- 0.004R), the geometry of the finished sheets deteriorated, and with a small concavity at the beginning of the working campaign, the wear of the other two rolls accelerated.

The use of parabolic equidistant generators did not significantly increase the yield of rolled products of the first grade, but reduced the maximum allowable duration of the working campaign of rolls by 10 ... 15%.

The device selected as the closest analogue was not used due to the uncertainty of the roll parameters. Thus, an experimental verification confirmed the acceptability of the technical solution found to achieve the goal and its advantage over a known object.

Feasibility studies have shown that the use of this utility model at OJSC MMK will increase the yield of high-quality thick sheets and the wear resistance of the rolls of the mill trio stand 2350 of the plant, which will reduce production costs by at least 12%.

Concrete example

The crate of the plate mill trio contains an upper and lower roll with a diameter of 950 mm and an average roll with a diameter of 550 mm (R = 275 mm).

The profile of the roll barrels during operation varies from convex to concave, and the roll gap remains constant due to the equidistance of the circular forming barrels.

The extreme value of the arrow forming the middle roll in the middle of the length of its barrel:

δ _c = ± 0.003R = ± 0.003 × 275≈0.08 mm.

Claims (1)

A crate of a trio plate mill containing upper, lower and middle rolls with a given configuration of their barrels, characterized in that at the beginning of the working campaign the barrels of the upper and lower rolls are made with a convex circular surface forming them having a maximum convexity δ in the middle of the barrel length, and forming middle roll barrel surface equidistant by said generator, wherein the absolute value δ is _a middle roll values δ, modifying its barrel surface, the extent of wear of the upper and lower roll barrels, from all mentioned before the convex and _with extreme values δ are within ± 0,003R, where R - radius of the middle roll barrels.