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Abstract

The table of contents

Introduction

To broadband mill hot rolling (WS HRM) are multistand mills with the placement of stands in the roughing and finishing groups. In the roughing group is used as irreversible and reversible crate located discontinuously or continuously, and in the finishing group of stand is always located continuously. All the products in wide-strip rolling mills is wound in rolls on reels.

Plate Rolling shop No. 2- Mill 2000

Figure 1 – Plate Rolling shop No. 2 - Mill 2000

Mill "2000" (figure 1) is used for the production of metal for different purposes: for the automotive industry, shipbuilding, fuel and energy complex (FEC), engineering, electrical and defense industries. Structurally divided into 2 sections – rolling production and finishing of sheet.

Rental Department consists of:

1. The area of the heating furnace.

2. Mill "2000". Designed for the production of rolled products with thickness from 1.2 mm to 16 mm, width from 900 to 1835 mm.

3. The plot of electroslag welding. Designed for the production of two - and three-layer slabs with subsequent rolling. The entire assortment of coils rolled from slabs from carbon, low-alloy, high-quality, stainless and other steel grades, chemical composition meets the requirements of the relevant state standards.

office of the decoration sheet is:

1. Slitting unit No. 1. Designed for longitudinal cutting of coils with thickness from 1.2 to 8.0 mm, widths from 900 to 1850 mm.

2. The cross cutting units No. 2, 3, 4. Designed for transverse cutting of coils with thickness from 1.2 to 16.0 mm, width from 900 to 1850 mm.

3. The plot of hot rolled coils. On the plot is the cooling, handling, packaging and shipment of the roll mill "2000" and unit cross cutting No. 1 (APR-1).

4. Phase formation and shipment of the sheet. The plot is packaging and shipment of products with cross cutting units.

Plate Rolling shop No. 2 - A Warehouse of the finished products

Figure 2 – Plate Rolling shop No. 2 - A warehouse of the finished products

1. Theme urgency

The shape of the ends of the roll and limit the amount of trim depends on the nature of the distribution of the reduction by the horizontal rolls roughing stands broadband mill hot rolling.

the amount of metal in the end pieces at mills horizontal rolling all universal roughing stands depends on the ratio of compression in the vertical rollers to compression in the horizontal rollers.

it is Known that the form of roll after compression in the horizontal rollers is convex, and then the vertical rolls concave. End trimming is 15-25% of the total consumption of metal (1,04-1,05).

Therefore at present an urgent task during rolling of strips on wide-strip rolling mills is the reduction of end trim of roll, as it allows to reduce metal consumption and energy for the rolling of strips.

the Issue of distribution of reductions in the draft stands (passes) broadband mills devoted a large amount of literature. As a rule, the main criteria for the distribution of reductions was adopted by the uniformity of load mechanical and electrical equipment roughing stands relative to permissible values. Taking into account these criteria in the current technological instructions for the rolling of slabs in roughing group of stands broadband mill provides the acceptable ranges of relative reductions in the stands. In the distribution of the thickness of roll stands in the roughing stands broadband mill enables loading of the stands in proportion to the allowable capacities used curves of specific energy consumption. Compression can be distributed in the stands (passes) and uneven.

From the technical literature it is known that the optimum ratio a/N providing the shape of the ends of the roll close to rectangular is 0.6-0.8. Work in this direction is performed only for a narrow range of the ratio of slab width B to the thickness H (for rolling in the first roughing stand), and only when the compression in the vertical rollers of smooth cylindrical barrel. The influence of the relations/N on the universal stands in the form of roll at the exit of roughing stands has not been investigated. In this regard, the work is relevant, as are aimed at reduction end trim.

2. The analysis of methods of distribution of reductions in the stands of the roughing group broadband hot rolling mill

In practice, there are several methods of distribution of reductions in the stands of the roughing group of stands of WS HRM. There are three methods of distribution of reductions on the horizontal rolls: distribution of reductions in the equal relative reduction; distribution of reductions at a given relative compression in the last stand and equal relative reductions in the previous stands; the distribution of thicknesses and compressions along the horizontal stands for the condition of uniform relative loading of crates according to different constraints. Together with the selected method of distribution of the reduction by the horizontal rolls method of distribution of reductions by vertical rolls.

We know that the nature of the distribution of the reduction by the horizontal rolls roughing stands broadband mill hot rolling depends on the shape of the ends of the roll in the plan, and, consequently, the value of the end trim. Reducing end trim is important as it allows to reduce metal consumption and energy for the rolling of strips.

As practice shows, the most optimal method of distribution of reductions to WS HRM is the method of distribution of thicknesses and compressions along the horizontal stands for the condition of uniform relative loading of crates according to different constraints. The criterion of optimal distribution of reductions in horizontal rolls (GW) roughing stands, you can accept one of the conditions of uniformity of loading of the equipment roughing stands, relative values of electric motors of main drives – power; the main lines – torque; roller systems – power rolling etc.

3. Method of research

3.1 General description of the program UNIVERSAL

the software Package "Universal" (version 4.2) is used to calculate the parameters of hot-rolling strip mill of arbitrary configuration. The program is developed in Windows environment and it takes about 3 MB of disk space.

the User of the package can form the mill desired configuration and for the mill to perform the calculation. The configuration of the mill is formed of standard objects (cars).

the roller and the screen is entered in the configuration of the mill automatically (i.e. the user should not enter them).

the Algorithm makes no restrictions on the number of objects, their order, the sequence of execution and the number of technological operations. This opportunity provides a modular structure of the algorithm, in which the modules are standard objects with mutually compatible inputs and outputs. The connection sequence of objects in the calculation is controlled by a dedicated array based on the scheme of rolling, the given user.

unlike the algorithm package UNIVERSAL puts certain restrictions on the number of objects and operations. They are caused by the size of the screen of the monitor, which should be placed the scheme of the mill, and reasonable considerations.

In version 4.2, the maximum number of objects (cars) – 35, number of operations is 100, the maximum number of passes in a single object, 25. If necessary, these restrictions can be changed.

The scheme of mill 2000 in the UNIVERSAL program

Figure 3 – The scheme of mill 2000 in the UNIVERSAL program

the Program allows to calculate the modes of the mills of arbitrary configuration is intended for production of rolled products including: crate, furnace winder, rewinding device, the shielding system of the peals, hydrobia, the installation of the cooling band. It calculates the rolling conditions, the calculation of temperature and power parameters, the calculation of deformation of the roll during rolling in the vertical and horizontal stands, as well as the technological requirements for basic equipment. A feature of mathematical software is the possibility of accounting for mill work on complex speed diagram of rolling, including five sections with constant but different levels of speed, alternating with areas of acceleration and deceleration; account for the dependence of the thermophysical characteristics of the metal from temperature.

based on the mathematical model of calculation of power parameters adopted in the model used previously in a widely tested program of ASPARN.

3.2 The results of the study

the criterion of optimal distribution of reductions in the GW roughing stands, you can accept one of the conditions of uniformity of loading of the equipment roughing stands, relative values of electric motors of main drives - power; the main lines - torque; roller systems -power rolling etc.

Loading the crates by the force of the rolling

Figure 4 – Loading the crates by the force of the rolling

Adamiecki's Graph

Figure 5 – Adamiecki's Graph

Conclusions

The above ways of distribution of reductions are optimal only for one selected condition of uniformity of loading equipment work stands. They do not take into account qualitative parameters of the technological process: the uniformity of the relative loading of the crates on other power parameters; total mass trim front and rear ends of the strip; the total power consumption, forces and torques of the rolling stands in the roughing group; lowering the temperature of metal in the cycle of rolling the slab in the roughing group and others.

In the future, our research task to evaluate all the above ways of distribution of reductions on a horizontal rough mill stands with the use of optimum complex criterion that takes into account quality and economic performance.

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