A method of manufacturing a hot-rolled strip for the production of cold rolled strips of anisotropic electrical steel

 

The invention relates to ferrous metallurgy and can be used in the manufacture of electrical steel strips. The technical result is the reduction of metal consumption in the manufacture of steel for the production of cold rolled strips of anisotropic electrical steel. For this purpose, the method of manufacturing a hot-rolled strip for the production of cold rolled strips of anisotropic electrical steel comprising heating billets, hot rolling, cooling, preparation before cold rolling and cold rolling, hot rolling in the finishing mills are working rolls, the edges of which have bevels size 0.1-0.6 mm in diameter of the roll, and a length defined from the expression: l-(L-B)/2+(0,015-0,070)In (mm), where l is the length of the bevel, mm; L - work roll barrel length, mm; width, 1 mm Il., table 1.

The present invention relates to ferrous metallurgy and can be used in the manufacture of electrical steel strips.

Closest to the proposed technical solution to the technical essence and the achieved result (prototype), according to the authors, is a method of manufacturing hot is the book H.F. Dubrova and N. I. Lapkina "Electrical steel" State scientific and technical publishing house of literature on ferrous and non-ferrous metallurgy, Moscow, 1968, UDC 669.14.048.5, pages 184-194.

From the description given in the book mentioned above, it follows that the method of manufacturing strips for the production of cold rolled strips of anisotropic electrical steel involves heating of the slab, hot rolling, cooling, preparation before cold rolling, which includes cutting edges, and cold rolling.

A disadvantage of the known technical solution is that in most cases, hot-rolled strip intended for redistribution on cold-rolled anisotropic electrical steel sheets, have the marginal thickness (clinoid shape), which is due to increased elastic deformation of the work rolls and their increased wear on parts (barrel length) in contact with the edges of the rolled strip.

According to the data given in the book by C. F. Lifanova "Rolling transformer steel, metallurgy, M., 1975, pages 180 and 181, Fig. 53, when receiving on reversing mill 1200 with winders in heating furnaces strips for producing strips of anisotropic electrical steel thickness of 2.5 e production of hot-rolled electrical steel strips according to the method, work rolls on the sections of the barrel corresponding to the edges of the strip, worn by 20-25% faster than in the middle part of the barrel. As a result, the shape of the gap between the work rolls and the shape of the transverse profile of the bands change over time in the rolling process. When rolling anisotropic electrical steel with high silicon content, the wear of the work rolls so intense that the shape of the gap and the shape of the cross-sectional profile of the bands varies greatly every 5-10 tonnes of rolled products. The nature of the wear of the work rolls after 20-25 tons of rolled takes the form of a box caliber (pages 178 and 179, Fig. 51), and the profile shape of the cross section of the bands changes from convex (lenticular) to flat and next to concave (at the end of the campaign working rolls). The clinoid shape of the edges (the difference in the thickness of the strip on the edge at a distance of 30 mm from it) in the production by a known method is 0.1-0,55 mm Increased wear of the work rolls in areas corresponding to the edges of the strip causes swelling on the strips at a distance of 100-125 mm from the edges and increase the clinoid shape edges to 0.3 mm

During the subsequent cold rolling of hot-rolled strips with tension, navigates tears, which lead to the strip breaks, emergency stop mill, increase the flow of metal. This phenomenon is particularly true for the production of anisotropic electrical steel having a high content of silicon in its composition and as a consequence reduced ductility in cold rolling. In the known technical solution, the tears on the edges of the original hot-rolled strip of anisotropic electrical steel prior to cold rolling, eliminate method of trimming.

In addition, changes in the cross-sectional profile strips in the hot rolling process causes a significant deviation of the shape from flat strips (warping, waviness) during cold rolling, which is not fully corrected in the further processing in the through-type furnaces and units continuous annealing.

When using the known technical solutions and conducting cold rolling of strips with the above value of the clinoid shape edges and with their pre-pruning, the above-mentioned factors lead to increased consumption of hot-rolled strip (discharge coefficient for the metal), the increase in the cost of its manufacture, as well as lower quality strips flatness, accounts for the technical solution, - reduction of metal in the manufacture of steel for the production of cold rolled strips of anisotropic electrical steel. When this is achieved the receipt of such technical result as improving the quality of cold rolled strips of anisotropic electrical steel by improving their flatness and reduce their production cost by reducing the expenditure ratio.

The above disadvantages are eliminated by the fact that in the method of manufacturing a hot-rolled strip for the production of cold rolled strips of anisotropic electrical steel comprising heating a slab, hot rolling, cooling, preparation before cold rolling and cold rolling, hot rolling in the finishing mills are working rolls, the edges of which have bevels size 0.1-0.6 mm in diameter of the roll, and a length defined from the expression: l=(L-)/2+(0,015-0,070)In (mm), where l is the length of the bevel, mm; L - work roll barrel length, mm; band width, mm

Comparative analysis of the proposed technical solutions with the prototype shows that the claimed method differs from the known fact that hot rolling in the finishing mills are working rolls, the edges to the 0)In (mm), where l is the length of the bevel, mm; L - work roll barrel length, mm; band width, mm

Thus, the claimed method meets the criteria of the invention of "Novelty."

Comparative analysis of the proposed solutions not only prototype, but also with other technical solutions revealed that the ways of rolling with rolling rolls having bevels on the edges, is widely known. However, the introduction of the work rolls with bevels with certain geometrical parameters in the method of manufacturing a hot-rolled strip for the production of cold rolled strips of anisotropic electrical steel and the relationship with other operations of the technological process allows not only to reduce the consumption of metal, but also to improve the quality of strips of anisotropic electrical steel and reduce the cost of production.

It follows that the claimed combination of significant differences provides obtaining mentioned technical result that, in the authors ' opinion, meets the criteria of the invention "Inventive step".

The proposed solution will be clear from the following description and the attached drawings: the drawing shows a diagram of rolling strips for production is Westside as follows. A slab of anisotropic electrical steel, obtained on machines continuous casting machine (CCM), is heated in the reheating furnaces, and rolled in several passes in the roughing reversing mill stand DUO received the workpiece is transported to the reversing finishing stand with winders in heating furnaces and rolled over several passes. This hot rolling in the finishing stands are working rolls 1, the edges of which have slanted "I" size 0.1-0.6 mm in diameter of the roll, and a length defined from the expression:
l=(L-B)/2+(0,015-0,070)(In (mm)
where l is the length of the bevel, mm;
L - work roll barrel length, mm;
In - band width, mm

After hot rolling strip of anisotropic electrical steel is cooled at a discharge roller and wound on the terminal winder in rolls. After cooling to a temperature of 50-60^oTo produce etching of the surface of the strips in a continuous pickling line and their preparation for the first cold rolling, which includes the tenderloin end sections, consolidation rolls welding "butt", oiling the surface, while trimming the lateral edges do not produce. Then make the first cold rolling in a continuous rolling mill and subsequent surgery of the Sabbath.

Thus, by rolling strips of anisotropic electrical steel in finishing stands quarto, the elastic deformation of the work rolls and their aforementioned bevels, under the joint effect, lead to the fact that the marginal zone is not subjected to excessive strain and wear of the rolls in this zone is reduced, compared with the known solution, and becomes uniform along the entire length of the roll barrel, the value of the clinoid shape of edges is within acceptable limits, and the need for trimming disappears.

If the size of the bevel on the diameter of the roll amount value less than 0.1 mm, and the length "l" value less than 0,015In (mm) of the above respective intervals, increased wear of the work rolls in areas corresponding to the edges of the strip, does not resolve that, as stated above, leads to thickening of bands and increase the clinoid shape edges.

If the size of the bevel on the diameter of the roll amount to the value of more than 0.6 mm, and the length "l" is the value of over 0,070In (mm) of the above respective intervals, then the marginal area of the rolled crimped enough, the marginal area of the knee is extended compared with its cf is the quality of the band and the downtime of the machines.

Thus, in the manufacture of steel for the production of strips of anisotropic electrical steel of the proposed method achieves a uniform wear of work rolls barrel, the nature of the wear of the work rolls, as shown by the results of the study slightly differs from the original (machine) profiling. Consequently, the cross-sectional shape of hot rolled strips in the hot rolling process varies slightly and is optimal (lenticular) for cold rolling, and the clinoid shape of the edges does not exceed the desired value.

The effectiveness of the proposed method is that during hot rolling, get the tackle with a stable cross-sectional profile and a reduced clinoid shape of the lateral edges need trimming are in the process of preparation of metal prior to cold rolling is eliminated, resulting in reduced consumption of metal.

Example
At the plate mill 1 OJSC NLMK 1200 mill was conducted by an experienced manufacturer of tackle for producing strips of anisotropic electrical steel.

The starting material for the production of hot-rolled strip was a slab of anisotropic electrical steel section 150

The slabs were heated in the reheating furnaces dvuhkletevogo mill 1200 at a temperature in the zones of the furnace within 1300-1340^oC for 5 h 14 min and rolled five passes in a reversing roughing universal stands DUO on the roll section 17,31020 mm Burst on to the intermediate conveyor conveyed to the reversing finishing stand quarto with winders in heating furnaces and rolled in three passes on the strip cross-section 2.51020 mm with a relative compression in the last passage within 42-45%. When rolling in the finishing stands used work rolls with barrel length, 1200 mm, with bevels on the edges, equal to 0.3 mm in diameter of the roll, and a length "l" equal to 120 mm, determined from the expression:
l=(L-)/2+(0,015-0,070)In=(1200-1020)/2+0,031020=120 mm,
where l is the length of the bevel, mm;
L=1200 - work roll barrel length, mm;
In=1020 - strip width, mm

After rolling on the delivery table was cooled with water to a temperature in the range 550-600^oTo and wound on the terminal winder in rolls. Then the hot-rolled coils were transferred to a cold rolling, where, after cooling to a temperature of 50-60^oLane asked in a continuous grass is TCE, which was the cut end sections of the bands, the escalation of the coils of welding "butt" and oiling the surface. While trimming the lateral edges of the strips was carried out. Then tackle for producing strips of anisotropic electrical steel rolled on a continuous pjatikletevoj 1200 mill thickness 0.70 mm and made all the necessary operations provided the technological process in the manufacture of strips of anisotropic electrical steel.

In the rolling process of an experimental batch of strips for producing strips of anisotropic electrical steel according to the proposed technical solution, in the visual inspection revealed no tears edges, and the measurement results confirmed their minimum thinning (clinoid shape of the edges was 0.05 mm and less). In cold rolling on pjatikletevoj the camp to the other units in the course of the technological process, gusts strip occurred.

Thus, in the manufacture of steel for the production of strips of anisotropic electrical steel of the proposed method achieves a uniform wear of work rolls barrel, while the profile of worn work rolls slightly differently is an ode to hot rolling is changed slightly and is optimal (lenticular) for cold rolling, and the clinoid shape of the edges does not exceed 0,05 mm

The effectiveness of the proposed method is that during hot rolling, get the tackle with a stable cross-sectional profile and a reduced clinoid shape of the side edges, the need to cut them in the preparation of metal prior to cold rolling is eliminated, resulting in reduced metal consumption, improving the quality of cold rolled strips of anisotropic electrical steel, reduced the cost of its production.

Therefore, the problem to solve which is directed technical solution is performed, thus achieves the above technical result.

Claims

A method of manufacturing a hot-rolled strip for the production of cold rolled strips of anisotropic electrical steel comprising heating a slab, hot rolling, cooling, preparation before cold rolling and cold rolling, wherein the hot rolling in the finishing mills are working rolls, the edges of which have bevels size 0.1-0.6 mm in diameter and roll length determined from the expression

l-(L-B)/2+(0,0150,070)