A rolling process of high-silicon non-oriented silicon steel thin strip

Abstract

The application discloses a rolling process of high-silicon non-oriented silicon steel thin strip and belongs to the technical field of cold rolling. The process comprises the following specific processes: hot coil silicon steel with a silicon content of not less than 3% is rolled by using a six-high reversing mill, and the rolling pass is 5-7 times; wherein, the work roll profile of the six-high reversing mill adopts a small crown roll, the roll profile crown is 20-30 mu m, and the roll profile insertion amount is 100-140 mm; the rolling oil is general cold rolling oil, and is configured into an emulsion with a temperature of 45-60 DEG C and a concentration of 2-4%; and the like. Through unique and reasonable matching design of multiple process parameters, batch stable production of the thin strip silicon steel (0.25-0.35 mm) with a silicon content of greater than 3% is realized on the six-high reversing mill, the production cost is reduced, the product competitiveness is improved, and the rolling efficiency is also improved compared with a 20-roll mill.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of cold rolling, and more particularly relates to a rolling process of high-silicon non-oriented silicon steel thin strip. BACKGROUND

[0002] In the field of steel, non-oriented silicon steel with a silicon content greater than 3% belongs to high-grade silicon steel, which is widely used in the manufacture of cores of high-performance motors and new energy automobile drive motors. The silicon steel sheet used in the core of the new energy automobile drive motor is a thin strip steel with a thickness less than 0.35 mm. In the cold rolling process of the thin strip steel, as the thickness is reduced, the degree of work hardening will increase sharply, and the required rolling force will also increase accordingly, which will cause the load of the cold rolling mill to be too high to start in several passes after cold rolling, and even if it starts, it will also cause the problem of difficult control of the wave shape after starting. Moreover, due to the high silicon content, the processability is poor, and the thin strip steel is prone to edge cracking and breaking during cold rolling.

[0003] Therefore, in order to realize the rolling of high-silicon thin strip, the high-grade thin strip silicon steel with a silicon content greater than 3% is mainly rolled by a 20-roller rolling mill at present. This is because the 20-roller rolling mill has a small work roll diameter, and can realize the rolling of thinner steel strips. However, the investment of the 20-roller rolling mill is large, it is difficult to build in a short time, and the maintenance cost is also much higher than that of the rolling mill with fewer rollers, and the production efficiency is lower than that of the rolling mill with fewer rollers. Therefore, how to realize the rolling of high-silicon thin strip with a silicon content greater than 3% on a rolling mill with fewer rollers has become an important problem in the field of cold rolling to improve efficiency.

[0004] A 20-roller rolling mill cooling equipment and a high-grade oriented silicon steel preparation method are disclosed in a patent document with the Chinese patent application number CN201711348250.4 and the publication date of June 5, 2018, which belongs to the field of high-grade oriented silicon steel manufacturing equipment and technology. A 20-roller rolling mill cooling equipment is designed, and the flow of emulsion is controlled by the cooling equipment, and the reduction deformation and rolling speed are cooperated with each other, so as to strictly control the temperature of the rolled steel strip in each rolling process. Five passes of repeated rolling are adopted to ensure the further refinement of the grain size of the rolled steel strip and the consistency of the grain orientation, and a high-magnetic oriented silicon steel product with a thickness of 0.23 mm is manufactured. At the same time, an independent oil-gas cooling system device for backing bearings is established, and the service life of the backing bearings can be significantly improved by using the device. In this scheme, the 20-roller high-roller rolling mill is generally used to roll the high-grade silicon steel, which has the problems of large investment, long construction time, high maintenance cost and low rolling efficiency.

[0005] The patent document with the Chinese patent application number CN202210524268.X and the publication date of July 12, 2022 discloses a cold rolling method for non-oriented silicon steel, in which the tension F(x) between the xth and x+1th stands during rolling is set as: F(x) = (A0 + B0x) + (A1 + B1x)([Si] - 0.8%) + (A2 + B2x)([Al] - 0.2%), where x = 1, 2, 3, 4;

[0006] A0: a tension fixed value preset according to the cold rolling mill; B0: a tension additive coefficient between the xth stand and x+1th stand preset according to the cold rolling mill due to work hardening; A1 and A2 are respectively fixed influence coefficients of the tension preset according to the Si and Al contents in the non-oriented silicon steel; B1 and B2 are respectively tension additive coefficients between the xth stand and x+1th stand preset according to the Si and Al contents in the non-oriented silicon steel under the influence of work hardening; [Si] is 0.8-1.2%, and [Al] is 0.2-0.5%. The present application adjusts the tension between each stand according to the silicon and aluminum contents, so that the rolling force of each stand and the tension between stands cooperate to stabilize the rolling process. Although this scheme uses a six-high low roll number rolling mill, the silicon content of the silicon steel it targets is 0.8-1.2%, which does not belong to high-grade silicon steel, and the final rolled strip thickness is 0.5mm, which also does not meet the use requirement of thickness not higher than 0.35mm. That is, the six-high low roll number rolling mill can be used because the product requirement is not high, so this scheme is not suitable for rolling high-grade silicon steel thin strips. SUMMARY

[0007] 1. Problem to be solved

[0008] To solve the problem that existing low roll number rolling mills are difficult to roll non-oriented high-grade silicon steel thin strips (0.25-0.35mm) with silicon content greater than 3%, the present application provides a rolling process for high-silicon non-oriented silicon steel thin strips, which stably produces batches of thin strip silicon steel (0.25-0.35mm) with silicon content greater than 3% on a six-high rolling mill by uniquely and reasonably matching multiple process parameters, reduces production cost, improves product competitiveness, and improves rolling efficiency compared to a 20-high rolling mill.

[0009] 2. Technical solution

[0010] To solve the above problems, the present application adopts the following technical solution.

[0011] A rolling process for high-silicon non-oriented silicon steel thin strips, the specific process is as follows:

[0012] A six-high reversible rolling mill is used to roll hot coil silicon steel with a silicon content of not less than 3%, and the rolling pass is 5-7 times.

[0013] The work rolls of the six-roll reversible mill are small-convex rolls with a roll convexity of 20-30 μm and an insertion depth of 100-140 mm.

[0014] The rolling oil used is general cold rolling oil, and it is prepared as an emulsion with a temperature of 45-60℃ and a concentration of 2-4%.

[0015] As a further improvement to the technical solution, the silicon content of the hot-rolled silicon steel is 3.0-3.5%, the thickness of the hot-rolled steel is 2.0-2.5 mm, and the width of the hot-rolled steel is 1000 mm-1200 mm.

[0016] As a further improvement to the technical solution, the working roll diameter of the six-roll reversible mill is greater than 230mm, and the roughness Ra of the roll is 0.3~0.7μm.

[0017] As a further improvement to the technical solution, when rolling hot-rolled silicon steel, the final rolling thickness is 0.35mm when using 5 passes, 0.3mm or 0.25mm when using 6 passes, and 0.25mm when using 7 passes.

[0018] As a further improvement to the technical solution, the inlet unit tension of the six-roll reversible rolling mill is 40–150 N / mm. 2 .

[0019] As a further improvement to the technical solution, the exit unit tension of the six-roll reversible rolling mill is 80–180 N / mm. 2 .

[0020] As a further improvement to the technical solution, the rolling speed of the six-roll reversible rolling mill is 400-1000 m / min.

[0021] As a further improvement to the technical solution, the emulsion flow rate of the six-roll reversible mill is 3500-6000 L / min.

[0022] As a further improvement to the technical solution, the reduction rate of the first 5 passes shall not be less than 25%.

[0023] As a further improvement to the technical solution, during the rolling process of the six-roll reversible mill, the inlet unit tension, outlet unit tension, rolling speed, and emulsion flow rate of the next pass are not lower than those of the previous pass.

[0024] 3. Beneficial effects

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] This invention discloses a rolling process for high-silicon non-oriented silicon steel strip. By rationally matching the roll profile, roll roughness, emulsion temperature and concentration, and other key parameters in the rolling procedure, it is possible to achieve stable batch rolling of thin silicon steel strip (0.25-0.35mm) with a silicon content greater than 3% on a six-roll reversible mill. The quality of the produced steel products is comparable to that of the same type of silicon steel produced by a twenty-roll mill, and the production efficiency is improved compared to the twenty-roll mill, thereby reducing production costs and enhancing product competitiveness. Detailed Implementation

[0027] Exemplary embodiments of the present invention are described in detail below. While these exemplary embodiments have been described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be implemented and various changes may be made to the invention without departing from its spirit and scope. The more detailed description of embodiments of the invention below is not intended to limit the scope of the claimed invention, but is merely illustrative and does not limit the description of the features and characteristics of the invention, in order to suggest the best mode for carrying out the invention and to enable those skilled in the art to practice it. Therefore, the scope of the invention is defined only by the appended claims.

[0028] A rolling process for high-silicon non-oriented silicon steel strip is provided to achieve stable mass production of thin silicon steel strips (0.25-0.35mm) with a silicon content greater than 3% on a low-roll mill. The specific process and technical effects are described in detail below.

[0029] The core improvement of this rolling process lies in achieving stable batch rolling of thin strip silicon steel (0.25-0.35mm) with a content greater than 3% on a six-roll reversible mill by reasonably matching the roll type, roll roughness, emulsion temperature and concentration, and other key parameters in the rolling procedure.

[0030] Specifically, a six-roll reversible rolling mill is used to roll hot-rolled silicon steel. The silicon content of the hot-rolled silicon steel is 3.0-3.5%, the thickness of the hot-rolled steel is 2.0-2.5 mm, and the width of the hot-rolled steel is 1000 mm-1200 mm.

[0031] The rolling passes are 5-7. When using 5 passes, the final rolling thickness is 0.35mm. When using 6 passes, the final rolling thickness is 0.3mm or 0.25mm. When using 7 passes, the final rolling thickness is 0.25mm.

[0032] To address the mill start-up issue under high rolling forces, a specialized work roll profile was designed to reduce the starting rolling force by preventing roll overlap under high rolling forces. Specifically, the work roll profile of the six-high reversible mill adopts a low-camber roll profile with a crown of 20–30 μm and an insertion depth of 100–140 mm. Simultaneously, the work roll diameter is greater than 230 mm, and the roll surface roughness Ra is 0.3–0.7 μm.

[0033] The rolling oil used is general cold rolling oil, and it is prepared as an emulsion with a temperature of 45-60℃ and a concentration of 2-4%.

[0034] During rolling, the unit tension at the entrance of the six-high reversible rolling mill is 40–150 N / mm. 2 The unit tension at the outlet is 80–180 N / mm. 2 The rolling speed is 400–1000 m / min, the emulsion flow rate is 3500–6000 L / min, and the reduction rate for the first 5 passes is not less than 25%. It should be noted that during the rolling process, the inlet unit tension, outlet unit tension, rolling speed, and emulsion flow rate of the next pass are not lower than those of the previous pass.

[0035] Through the above-mentioned rolling process of high-silicon non-oriented silicon steel strip, on the basis of achieving stable batch rolling of thin silicon steel strip (0.25~0.35mm) with a silicon content greater than 3% using a six-roll reversible rolling mill, the quality of the produced steel products is comparable to that of the same type of silicon steel products produced by a twenty-roll rolling mill, and the production efficiency is improved compared to the twenty-roll rolling mill, thereby reducing production costs and enhancing product competitiveness.

[0036] To further understand the technical effects of the processing technology of this application, the implementation process and data from a specific production experiment are given below.

[0037] Example 1

[0038] The final rolled thickness is 0.35 mm. High-silicon non-oriented silicon steel strip.

[0039] 1) The hot-rolled product has a silicon content of 3.35%, a thickness of 2.2 mm, a width of 1200 mm, and is rolled into a 0.35 mm product through 5 passes.

[0040] 2) The working roll adopts a small crown roll with a crown of 30μm and an insertion depth of 140mm.

[0041] 3) The working roll diameter of the six-roll reversible rolling mill is 255mm, and the roughness Ra of the roll is 0.65μm.

[0042] 4) The rolling oil used is general cold rolling oil. The rolling oil is prepared into an emulsion at a temperature of 50°C and the emulsion concentration is 2.5%.

[0043] 5) The key parameters in the rolling table, such as reduction rate, front tension, back tension, rolling speed, and emulsion flow rate, are shown in Table 1.

[0044] Table 1: Rolling schedule for 0.35mm high-silicon non-oriented silicon steel strip

[0045]

[0046] Example 2

[0047] 1) The hot-rolled coil has a silicon content of 3.4%, a thickness of 2.2 mm, a width of 1150 mm, and is rolled into a 0.3 mm product through 6 passes.

[0048] 2) The working roll adopts a small crown roll with a crown of 25μm and an insertion depth of 120mm.

[0049] 3) The working roll diameter of the six-roll reversible rolling mill is 250mm, and the roughness Ra of the roll is 0.55μm.

[0050] 4) The rolling oil used is general cold rolling oil. The rolling oil is prepared into an emulsion at a temperature of 55°C and the emulsion concentration is 3.5%.

[0051] 5) Key parameters in the rolling table, such as reduction rate, front tension, back tension, rolling speed, and emulsion flow rate, are shown in Table 2.

[0052] Table 2: Rolling schedule for 0.3mm high-silicon non-oriented silicon steel strip

[0053]

[0054] Example 3

[0055] 1) The hot-rolled coil has a silicon content of 3.46%, a thickness of 2.0 mm, a width of 1100 mm, and is rolled into a 0.25 mm product through 6 passes.

[0056] 2) The working roll adopts a small crown roll with a crown of 20μm and an insertion depth of 100mm.

[0057] 3) The working roll diameter of the six-roll reversible rolling mill is 245mm, and the roughness Ra of the roll is 0.45μm.

[0058] 4) The rolling oil used is general cold rolling oil. The rolling oil is prepared into an emulsion at a temperature of 57°C and the emulsion concentration is 3.7%.

[0059] 5) Key parameters in the rolling table, such as reduction rate, front tension, back tension, rolling speed, and emulsion flow rate, are shown in Table 3.

[0060] Table 3: Rolling schedule for 0.25mm high-silicon non-oriented silicon steel strip

[0061]

[0062] By testing the performance parameters of the products finally rolled in the above three embodiments, such as strength and toughness, and comparing them with the performance parameters of high-grade silicon steel strip rolled by a 20-roll mill under traditional process conditions, it was found that the quality of the products rolled in the embodiments of this application is comparable, while the rolling efficiency has been effectively improved.

Claims

1. A rolling process for high-silicon non-oriented silicon steel strip, characterized in that: The specific process is as follows: Hot-rolled silicon steel with a silicon content of not less than 3% is rolled using a six-roll reversible rolling mill, with 5-7 rolling passes. When rolling hot-rolled silicon steel, the final rolling thickness is 0.35 mm when using 5 passes, 0.3 mm or 0.25 mm when using 6 passes, and 0.25 mm when using 7 passes. The work rolls of the six-roll reversible mill are small-convex rolls with a roll convexity of 20-30 μm and an insertion depth of 100-140 mm. The working roll diameter of the six-roll reversible rolling mill is greater than 230 mm, and the roughness Ra of the roll is 0.3 to 0.7 μm; The rolling oil used is general cold rolling oil, and it is prepared as an emulsion with a temperature of 45-60℃ and a concentration of 2-4%.

2. The rolling process for high-silicon non-oriented silicon steel strip according to claim 1, characterized in that: The hot-rolled silicon steel has a silicon content of 3.0-3.5%, a thickness of 2.0-2.5 mm, and a width of 1000-1200 mm.

3. The rolling process for high-silicon non-oriented silicon steel strip according to claim 2, characterized in that: The unit tension at the entrance of the six-roll reversible mill is 40~150 N / mm².

4. The rolling process for high-silicon non-oriented silicon steel strip according to claim 3, characterized in that: The unit tension at the exit of the six-roll reversible rolling mill is 80~180 N / mm².

5. The rolling process for high-silicon non-oriented silicon steel strip according to claim 4, characterized in that: The rolling speed of the six-roll reversible rolling mill is 400~1000m / min.

6. The rolling process for high-silicon non-oriented silicon steel strip according to claim 5, characterized in that: The emulsion flow rate of the six-roll reversible mill is 3500~6000L / min.

7. The rolling process for high-silicon non-oriented silicon steel strip according to claim 6, characterized in that: The reduction rate for the first 5 passes shall not be less than 25%.

8. The rolling process for high-silicon non-oriented silicon steel strip according to any one of claims 3-7, characterized in that: During the rolling process of the six-roll reversible mill, the inlet unit tension, outlet unit tension, rolling speed, and emulsion flow rate of the next pass shall not be lower than those of the previous pass.

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