JPH03271323A - Production of nonoriented silicon steel sheet - Google Patents

Abstract

PURPOSE:To improve the magnetic properties of a nonoriented silicon steel sheet by measuring the iron loss of a finish-annealed steel sheet with respect to the longitudinal direction and its crossing direction and regulating and controlling the tension of a steel sheet based on the resulting measured values. CONSTITUTION:A hot rolled plate stock for nonoriented silicon steel sheet is cold-rolled once or is cold-rolled twice while process-annealed between the cold rolling stages so as to be worked to the final sheet thickness, and finish annealing is exerted under the tension in the longitudinal direction of the steel sheet. At this time, iron loss is measured with respect to the longitudinal direction and its crossing direction of the finish-annealed steel sheet. The tension of the steel sheet is controlled so that the average value of the resulting measured values is at a minimum. Further, the iron loss ratio C/L is determined from the iron loss data measured with respect to the longitudinal direction L and its crossing direction C, and the tension to be applied in the course of finish annealing is controlled so that the iron loss ratio based on measurement agrees with the iron loss ratio where the average value of the iron losses in respective directions after finish annealing previously determined is at a minimum.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for producing a non-oriented electrical steel sheet that is particularly suitable as a core material for rotating equipment such as electric motors and generators. be.

(Prior Art) JP-A-1-92318 discloses a method for producing a non-oriented electrical steel sheet in which magnetic anisotropy is reduced by cold rolling a copper strip in the longitudinal and width directions. Although,
Rolling in the width direction is impractical and difficult to apply to industrial production.

Furthermore, in JP-A-62-102507, the appropriate range of threading tension during finish annealing is defined as a function of finish annealing temperature and soaking time, and the magnetic direction ratio in the rolling direction and the direction perpendicular thereto is A method of obtaining a non-oriented silicon steel sheet with small and excellent magnetic properties by short-time annealing is disclosed. However, this method stipulates the range of threading tension, and it is impossible to determine a more suitable optimum threading tension.Furthermore, due to fluctuations in impurities such as S in the material, The optimal threading tension varies depending on the component composition due to differences in grain growth, but there are problems such as no consideration is given to this phenomenon.

(Problems to be Solved by the Invention) The purpose of the present invention is to improve the magnetic properties by appropriately performing final finish annealing in a method for manufacturing non-oriented electrical steel sheets, and to improve the iron loss value. The objective is to optimize the longitudinal steel plate tension during final annealing, which greatly affects the process, and to be able to respond to the optimum steel plate tension, which varies depending on the component composition and manufacturing conditions.

(Means for Solving the Problems) This invention provides a final finish that reduces the tension of the steel plate in the longitudinal direction during annealing and changes the composition of the steel plate so that the average value of iron loss in the longitudinal direction and the transverse direction of the steel plate is minimized The system adjusts and controls the tension to suit the optimum steel plate tension, which varies depending on the manufacturing conditions. After rolling to the final thickness, finish annealing is performed under tension in the longitudinal direction of the steel plate.The iron loss of the steel plate that has undergone finish annealing is measured in the longitudinal direction and the transverse direction of the steel plate. A method for producing a non-oriented electrical steel sheet, characterized in that the tension is controlled so that the average value is the lowest.

2. Using hot rolled sheets for non-oriented electrical steel sheets as raw materials, cold rolling is performed once or twice with intermediate annealing to achieve the final thickness, and then finish annealing is performed under tension in the longitudinal direction of the steel sheet. In applying this method, the iron loss ratio C/L is determined from the data measured in the longitudinal direction (L) and the transverse direction (C) of the steel plate that has undergone finish annealing, and the iron loss ratio C/L is determined by the iron loss ratio C/L that acts on the steel plate during finish annealing. The tension is adjusted to the iron loss ratio C/L that minimizes the average value of the iron loss in each direction after final annealing of the steel sheet, which is determined in advance according to the component composition and manufacturing conditions, and the iron loss ratio C/L based on the above measurement. A method for manufacturing a non-oriented electrical steel sheet, which comprises controlling the tension so that L is made to match.

It is.

Here, the average value of the iron loss in the longitudinal direction and its transverse direction, or the average value of the iron loss in each direction, is: Longitudinal iron loss value -----IRL Transverse direction perpendicular to the longitudinal direction---IRCo.

Transverse direction making an angle of 45° with the longitudinal direction---IRC4
5, it may be calculated as in equations (1) and (2) above, and furthermore, the iron loss value in the transverse direction with different angles to the longitudinal direction may be used, and the iron loss value in the transverse direction with different angles may be used. Many iron loss values may be used.

In addition, the iron loss ratio C/L represents longitudinal iron loss ÷ transverse iron loss, where the angle between the transverse direction and the longitudinal direction is 90°.
Anything other than that is fine.

The method of the present invention relates to the composition of a hot-rolled sheet for non-oriented electrical steel sheets, such that C≦0.05wtX Si+1≦4.5w
tX, Mn≦1.5wtX, and in some cases P: 0.05 to 0.20wtX, with the balance consisting of Fe and unavoidable impurities.

Here, when C > 0.05wt
> 4.5 wtX is unsuitable due to problems with workability during cold rolling, and Mn > 1.5 wtX increases production costs more than improving electromagnetic properties, which is a practical problem. Not compatible with P is 0.05 to 0.20 for the purpose of adjusting the hardness of the final product.
wtX is preferred.

(Function) In the production of non-oriented electrical steel sheets, the steel sheet tension during finish annealing has a large effect on the iron loss value, and when tension is applied in the longitudinal direction, the longitudinal iron loss value decreases, and the transverse direction , especially the iron loss value in the direction perpendicular to the longitudinal direction shows a tendency to increase. Then, there is a tension at which the average value of iron loss in the longitudinal direction and in the transverse direction is the minimum, that is, an optimum tension. Second
The figure shows these relationships in a transverse direction perpendicular to the longitudinal direction. The horizontal axis shows the steel plate tension and the vertical axis shows the iron loss value, and the longitudinal direction iron loss value (IRL) and the cross section are shown as parameters, and it can be seen that there is an optimal steel plate tension that minimizes the average value of iron loss. .

Next, between the average value of iron loss in the longitudinal direction and its transverse direction and the iron loss ratio (C/L), there is also an iron loss ratio (C/L) that minimizes the average value of iron loss. . Figure 3 shows these relationships.
The case of a longitudinal direction and a transverse direction perpendicular to the longitudinal direction are shown. The horizontal axis shows the iron loss ratio: Coo/L
, there is an iron loss ratio that minimizes the average iron loss value on the vertical axis.

On the other hand, as described above, the optimum steel plate tension for reducing the iron loss value varies depending on the component composition, manufacturing conditions, etc. Therefore, in order to perform finish annealing with the optimum steel plate tension, the most reliable method is to measure the iron loss of the steel plate after finish annealing and feed back the results.

In other words, in controlling the steel plate tension, based on the relationship shown in Figure 2 above, it is possible to effectively control the steel plate tension by dynamically feedback controlling the steel plate tension so that the average value of iron loss measured online immediately after finish annealing is the lowest. will be achieved.

Furthermore, from the relationship shown in FIG. 3 above, it is also possible to control the steel plate tension using the iron loss ratio that minimizes the average value of iron loss. In online measurement in actual production equipment, it is difficult to calculate the absolute value of the iron loss value and calibrate it, so it is advantageous to use an iron loss ratio that does not require calibration of the absolute value.

Furthermore, due to the characteristics of non-oriented electrical steel sheets, they are often used in rotating machines, and in order to reduce uneven rotation, it is desirable to reduce the iron loss ratio (C/L). In this method, the average value of iron loss is minimized. This is because, in large rotating machines or rotating machines that operate continuously for long periods of time, not only uneven rotation but also energy loss is important. This is because the minimum iron loss ratio (C/L) does not necessarily mean the minimum energy loss, and the energy loss can be minimized by minimizing the average value of the iron loss.

Hereinafter, a case will be described in which the tension is controlled in the final continuous annealing using the iron loss ratio.

FIG. 1 is a side view of a finishing continuous annealing furnace showing a control system. The steel plate cold-rolled to the final thickness moves continuously from left to right in the direction of the arrow. Steel plate l is finished in continuous annealing furnace 2
Finish annealing is performed by passing through. and,
Iron loss is measured by iron loss measuring devices 4 and 5 in the longitudinal direction and in the transverse direction, which are installed on the exit side of the finishing continuous annealing furnace 2. These measurement data are sent to the calculator 6, where the iron loss ratio (C/L) is calculated, and the optimum iron loss ratio (C/L) that minimizes the average iron loss value determined by the component composition, manufacturing conditions, etc. )
The difference between the two is detected. Then, based on this detection result, an instruction to increase or decrease the steel plate tension is output to the tension control circuit 7, and from this tension control circuit 7, the steel plate tension is adjusted via the tension control priddle roll 3, and the average iron loss is is controlled so that it is minimized.

(Example) After melting in a converter, RH degassing treatment was performed to change the chemical composition to C: 0.004 wtX Si: 3.1 wtX Mn: 0.3 wtX Aj7: 0.4 wtX S: 0 A silicon steel slab adjusted to .005 wtX P: 0.05 wtX and produced by continuous casting was hot-rolled into a hot-rolled plate with a thickness of 2.4 mm, and heated at 1000°C.
After annealing at a temperature of 1 minute, the final plate thickness was 0.5 mm.
Cold rolling was carried out.

The final finish annealing was performed at a temperature of 1000° C. for 30 seconds, and the steel plate tension was adjusted and controlled using an iron loss ratio that is advantageous when applied to an actual production process.

Figure 3 shows the iron loss ratio: Cso/L of the steel sheet determined by the component composition and manufacturing conditions, and the average value of iron loss (W + 5150).
It is shown that the optimum iron loss ratio with the minimum value is 1.10.

Using this optimal iron loss ratio, the steel plate tension was adjusted and controlled. That is, since the iron loss ratio at the beginning of finish annealing was 1.21, the steel plate tension was reduced and adjusted so that the optimum iron loss ratio was 1.10. Furthermore, as a precaution, the steel plate tension was reduced to reduce the iron loss ratio to 1.06.

Table 1 shows the average value of iron loss and steel plate tension in these cases.

As is clear from this table, the average value of iron loss is the minimum at the optimum iron loss ratio of 1°10, showing good agreement with the value determined from the component composition and manufacturing conditions.

Table 1 (Effects of the invention) In the production of non-oriented electrical steel sheets with excellent iron loss values, the present invention sets the steel sheet tension during final annealing to the minimum iron loss average value determined from the component composition and manufacturing conditions, or The iron loss ratio that minimizes the average value of iron loss is used, and the tension is adjusted and controlled while actually measuring the ratio.This technology can be advantageously used in the production of non-oriented electrical steel sheets in the future. .

[Brief Description of the Drawings] Fig. 1 is a side view of the finish annealing furnace showing the control system, and Fig. 2 shows the relationship between steel plate tension and iron loss value. FIG. 3 shows the relationship between the iron loss ratio in different directions and the average iron loss value. 1... Steel plate 2... Finishing continuous annealing furnace 3
...Pridle roll for tension control 4...Iron loss measuring device (longitudinal direction) 5...Iron loss measuring device (transverse direction) 6...Calculator 7...Tension control circuit 1
figure

Claims (1)

[Claims] 1. Using a hot rolled sheet for non-oriented electrical steel sheet as a raw material, cold rolling is performed once or twice with intermediate annealing to obtain the final thickness, and then finish annealing is applied to the steel sheet. When applying under tension in the longitudinal direction, the iron loss of the steel plate that has undergone finish annealing is measured in the longitudinal direction and the transverse direction of the steel plate, and the tension is controlled so that the average value is the lowest. A method for manufacturing non-oriented electrical steel sheets. 2. Using a hot-rolled non-oriented electrical steel sheet as a raw material, cold rolling it once or twice with intermediate annealing to achieve the final thickness, then finish annealing under tension in the longitudinal direction of the steel sheet. In applying this method, the iron loss ratio C/L is calculated from the data measured in the longitudinal direction (L) and the transverse direction (C) of the steel plate that has undergone finish annealing, and the iron loss ratio C/L is determined by the iron loss ratio C/L that acts on the steel plate during finish annealing. The tension is adjusted to the iron loss ratio C/L that minimizes the average value of the iron loss in each direction after finish annealing of the steel sheet, which is determined in advance according to the component composition and manufacturing conditions, and the iron loss ratio C/L based on the above measurement. A method for manufacturing a non-oriented electrical steel sheet, which comprises controlling the tension so that L is made to match.