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Abstract

Содержание

Introduction

Employment companies in a market economy, a large proportion of the cost of energy and raw materials in the structure of prime cost, highlight the problem of economical use of these resources. In metallurgy a large part of the waste generated in the final stage - in the rolling production, where the cost of the metal is highest. In Ukraine, for the production of steel plate is very relevant problem of reducing the waste metal and other technical and economic performance by as much as possible the modernization and reconstruction of existing TLS, the development of new advanced rolling technology. One of the main indicators of the effectiveness of a specific sheet metal consumption, which depends on several factors. Particular influence on the specific consumption of metal have a metal waste with the side and end trim, depending on the form of rolls obtained. Submitted in DonNIIchermet studies have shown that on average 85% of the waste and metal loss of lateral and end trimmings [1]. Thus, the search for and development of new ways to reduce the consumption of metal in the trimmings is an urgent task rolling production. This work is aimed at the development of methods for calculating the form of a peal in the plan.

1. Theme urgency

The level of sheet metal production indirectly determines the degree of industrial development of the country as a whole. In developed countries the share of flat steel production exceeds 60% of the total production of rolled products. The major component of sheet metal mix are thick sheets (thickness of 4 mm or more).

Ferrous metallurgy of Ukraine is characterized by high costs of energy and material resources, including the production of rolled products. This is especially true for sheet metal, as its share over the last decade in the total metalloproduktstsii continuously growing.

The average expenditure ratio in the metal plate mills in countries with modern rolling technologies at the level of 1175 kg/t, and in Japan on mills 5500-1085 kg/t. Whereas on the reversing plate mill Ukraine consumable coefficient ranges 1180-1285 kg/t.

Reduction of the metal flow during rolling plates reach most cases a decrease side and end trimmings rolls by controlling the shape in plan at the stage of roughing rolling. Existing control methods for rolling on the enterprises of Ukraine have not been implemented to date. Therefore, there is an actual scientific and technical problem of rational justification of the wide faces of profiling options and forms in terms of rolls in rolling plates in order to reduce the consumption of metal in the trimmings.

2. Goal and tasks of the research

The aim is to study the rational profiling parameters wide faces and forms of peals in the plan when rolling thick sheets, allowing to reduce the consumption of metal in the trimmings due to approximations form of ready sheet peals in the plan rectangular, and the creation of new metallosberegayuschih rolling method.

The main tasks of the research:

  1. To investigate the processes in terms of the forming rolls with horizontal rolling rolls in the roughing step by various methods broad profiling faces.
  2. A study of forming a concave and narrower end of roll when the metal deformation zone is full.
  3. Develop relationships for calculating the parameters of forming rolls in terms of when the profiled rolling, taking into account all the most significant factors in the actual rolling ranges of relevant for the majority of the existing plate mills.

Research object: the process of forming rolls to appear rectangular contour of the cross-sectional shape and in terms of the production of hot-rolled plates.

Subject of research:Forming ends of a peal in the plan at the stage of roughing rolling plates with profiling wide sides. The mathematical model of the process of forming rolls in the plan, ways of rolling plates.

3. Analytical review of the work in terms of roll formability during rolling in horizontal rolls

3.1 Forming blanks original rectangular shape in the plan

Because the rectangular shape in plan may only have the initial billet, consider the formability of dedicated work workpieces in one pass.

Analysis of forming rolls during the rolling process in the horizontal rolls a number of papers[1-14]. The main factor determining the form of a peal in the plan during rolling in cylindrical horizontal rollers is uneven deformation along the length and width of roll caused by operation of law «least resistance».

In the works of M. Pavlova [1, 2]first described «fanlike» broadening of the rolled strip end, given the qualitative explanation of this phenomenon is based on the theory «hard all» and the law «least resistance».

G. Arkulis [3, 4], exploring minimum length«hard all», He showed a difference in forming the front and rear areas of the transient process. Analytical methods for determining the value of the distribution «fan-shaped» broadening still little developed. The paper [5] attempt based on the methodology of A. Tselikov[6] and A. Gorshkova [7] calculate the expansion of the ends of roll with its single compression.

Conventionally, it is assumed that the end of the initial stage of the transient process of rolling coincides with the passage of the front end of the strip through the center of the line.>

The paper [8] found that the expansion of the ends of roll «extinguished» decreasing the thickness of roll and rolling at certain stages disappears. However, according to calculate the expansion is not shown.

The paper [9] the equations to determine the parameters of the form rolls. However, the description of the circuit uneven ends expressed in a circle, which is not always true.

The paper [10] shows a method of calculating the arrows convex front and rear ends of the sheet of roll when rolling thick sheets from slabs based on well-known hypotheses in the theory of rolling. The value is determined by the varying convexity hood longitudinal axis of roll and its lateral faces. Using the law of least resistance, and analytical dependences for areas broadening areas adjacent to the zones and timing lag [11], the author received expressions to define the edges of roll drawing, depending on the compression ratio.

As a form of roll parameters in terms of compression after a rectangular slab HB most welcome: arrows dished ends, their expansion (additional local broadening) and very rarely extended length sections.

В работе[12] shape parameters determined in terms of roll according to rolling criteria:

(1)

where - shape parameters of the front (rear) end of roll (the original rectangular slab after one passage in the horizontal rolls);

- coefficients

The proposed dependence (1) does not account for the influence of temperature of the metal, metal contact conditions - rolls rheology steel.

3.2 Forming rolls with a rectangular shape in plan

The literature mentioned a lot of work, which shows the empirical relationships to calculate certain parameters form the ends of roll after the compression slab in HB. In many of these definitions are listed according to the convexity or concavity of the ends of arrows as a function of the first coefficient and the second (most of their attitude) and some of the third and extracts characterizing broach respectively, and a longitudinal width breakdown rolling to a predetermined thickness[13-21].

Impact on raznoshirinnost of plate rolls fractional strain has been found in the [13], and in [22] V. Klimenko, E. Filippov et al. Obtained for the plate mill conditions 3600 formula, the structure of which entered the correction factors that take into account the ratio of the actual average reduction rate to the base at each stage of rolling.

A number of works devoted to the mathematical description of the form of peals in the plan [23-26]. Dependencies which are obtained by the author for the calculation of individual elements of a sheet of roll contour, or no options include rolling [25], or include the total exhaustion in stages, or at all stages of rolling. In this regard, the proposed mathematical models have no practical value because they can not perform the prediction function to be used in the control algorithms.

M. Cherner and A. Voropaev offered options form the ends of rolls when rolling on TLC approximately calculated by dependencies [20]:

(2)

где - arrow curvature of the front and rear end;

– bandwidth in the i-th passage of the front, the rear end;

– factor which takes into account the impact on the total exhaustion of roll drawing factor bands, location bands at the ends of rolls and the rolling direction of roll.

The disadvantage of working [20] It is that at the end of roll shape parameters are not taken into account the effect of width to thickness ratio of roll, as well as the ratio of the diameter to the thickness of the aisles. Not studied the expansion and the length of the extended end portions of roll down the aisles

In the works [26, 27]describes a method for studying and forming a mathematical description of all the parameters in terms of roll sheet in the dynamics of the aisles in the horizontal rolls, based on the use of the recurrent expressions and technological transfer coefficients.

Settings form ends of roll after any passage in the GW can be determined by applying the principle of superposition, as the sum of two components. The first component is the result of the deformation of the outer end of the second - conditional rectangular end of roll. The peculiarity of forming the ends of the inscribed rectangular end of roll is the presence in front of them incomplete rigid zones, reducing the unevenness of the width of the metal flow.

The proposed recursive expression for calculating the shape parameters of the front and rear end of roll, which has the form:

(3)

where - front shape parameters (n), back (h) after the end of roll horizontal rolling rolls (g) in i-pass that;

– the shape parameter of the front (rear) end of roll-front and the fifth passage;

– parameter forms the front (rear) end of the rectangular inscribed in a rolled after deformation is i-pass;

– shape parameter conditionally inscribed rectangular contour after deformation in the i-th pass.

– transmission coefficients (partial containment rigid outer contour areas) parameters rectangular conditionally inscribed rectangular peal in this passage;

A drawback of (3) is that it ignores the influence of non-uniform deformation across the width.

Conclusion

The work solved an important scientific and technical problem on substantiation of rational parameters of profiling wide sides and forms peals in the plan when rolling thick sheets in order to reduce the consumption of metal in the trimmings due to approximations form of ready sheet peals in the plan rectangular.

Basic scientific principles and practical results are as follows.

1. From the analysis of scientific literature shows that the theoretical and experimental investigations of the forming parameters are made either after a single compression rectangular blanks, or after the last pass at certain stages of roughing. They do not take into account the conditions of rolling with profiled wide faces. It determines the need for further theoretical and experimental studies in this field in terms of study profiling parameters wide faces and forms peals in the plan when rolling thick sheets on new metallosberegayuschim methods.

2. It is found that profiling compression at intermediate stages of rough rolling are more efficient than the early stages, and when the thickness ratio of roll stretching at a stage following after peal profilirovnaiya thickness over its length, and the ratio of roll length to thickness profiling before passage less. At the same time the effect of profiling the known and new methods of rolling about the same, but the value of profiling reductions for new process for less than 2-10 times.

maximum stroke of the plunger cylinder 50-60 mm, 40-60 mm Compression speed: In order to implement new ways of rolling a wide faces profiling (without reducing their effectiveness in relation to the known rolling methods) hydraulic jacking device with lower requirements to their characteristics can be used / s and the acceleration is not below 400-600 mm / s2.

3. It got a further development of the method for calculating the parameters of forming rolls all in terms of the aisles at the expense of processing in terms of recurrent components forming parameters with uneven compression in width. Expression allows the calculation of all the parameters of the form rolls in a profiled rolling the aisles, taking into account kantovok and reverses.

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