JPS61132205A - Cold rolling method of silicon steel sheet - Google Patents

Abstract

PURPOSE:To prevent the generation of sheet breakage and to improve the rolling efficiency and the product yield by setting the strip temperature of a silicon steel sheet containing the prescribed amount of silicon, at the inlet side of the 1st pass and the strip temperature between the outlet side of the 1st pass and a tension roll to the specific ranges respectively. CONSTITUTION:In rolling a silicon steel sheet containing <=1.5% Si, its strip temperature at the inlet side of the 1st pass is set to >=50-250 deg.C>=, by a heating equipment, etc. located at the inlet side of a rolling mill. Further in rolling the strip, its temperature between the outlet side of the 1st pass and a tension roll is set to >=100-250 deg.C>= by effectively utilizing the energy of rolling work in the 1st pass. Furthermore at need, the strip is successively rolled by setting its temperature between the outlet side of the succeeding pass after the 2nd pass and a tension roll >=100-250 deg.C>=.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for cold rolling silicon steel sheets.

[Prior Art] Conventionally, cold rolling of a silicon steel sheet involves a rolling mill 11, a winder 2, and a deflector roll 3, as shown in FIGS. 6(A) and CB).
, is carried out using rolling equipment equipped with tension rolls 4. When a silicon steel plate is rolled with such rolling equipment, the number of times the strip breaks is greater than that in a strip of ordinary steel plate, and the rolling efficiency and yield are low.

Therefore, a technique has been proposed for rolling a silicon steel plate without applying excessive bending, as shown in, for example, Japanese Unexamined Patent Publication No. 58-1!38115.

This conventionally proposed technique is based on the above-mentioned strip ”
This was done based on the knowledge that the breakage of the strip was due to bending that occurred in the strip in contact with the deflector roll, and the gist of this was as follows: (a) As shown in Figure 7, the strip was ejected from the rolling mill 5. In rolling equipment that winds a strip onto a winder 7 via a pair of upper and lower deflector rolls 6, a tangent line drawn from the deflector roll 6 to the drum 8 of the winder 7 and the deflector roll 6 are used.
The angle 0 between the deflector roll 6 and the pass line at the deflector roll 6 and the angle θ between the tangent drawn from the deflector roll 6 to the winding coil 9 at the maximum diameter and the pass line at the deflector roll 6 are each within 10 degrees. (b) In a rolling facility in which the strip discharged from the rolling mill 5 is wound onto the winding machine 7 via a pair of upper and lower deflector rolls 6, the above (a) The rolling equipment is equipped with a device that raises and lowers either or both of the deflector roll 6 and the winder 7 so that the angle is .

[Problems to be Solved by the Invention] However, in the above-mentioned conventionally proposed rolling methods, there are geometric restrictions between the deflector roll 6 and the winder 7, and the distance between the deflector roll 6 and the winder 7 is limited. A complicated device for raising and lowering one or both of the takers 7 is required.

Incidentally, the bending strain εf of the strip surface at the portion in contact with the deflector roll or tension roll is, in the case of a simple ridge, εf=z/2r (here).

2 is the thickness of the strip, and r is the roll radius of the deflector roll or tension roll. That is, by increasing the roll radius of the deflector roll or tension roll, the bending strain on the strip surface becomes smaller. Therefore, in this case, even if a fine rack occurs at the width end of the strip, the strip will not break because cracks will not grow, but the deflector roll radius and tandem mill stand The radius of the tension rolls disposed between them must be increased, resulting in an inconvenience in the installation space.

An object of the present invention is to prevent the occurrence of fracture when rolling a silicon steel plate without restrictions regarding the arrangement of rolling equipment or complicated equipment.

[Means for Solving the Problems] The first aspect of the present invention is that in a method for cold rolling a silicon steel sheet containing 1.5% or more of Si, the strip temperature on the first pass entry side is set at 50°C or more and 250°C. The strip temperature between the exit side of the first pass (stand) and the tension roll is set at 100° C. or higher and 250° C. or lower for rolling.

The second aspect of the present invention is a method for cold rolling a silicon steel sheet containing 1.5% or more of Si.
The strip temperature from the first pass exit side to the tension roll is set to 100°C or more and 250°C or less, and then the strip temperature is set at 100°C or more and 250°C or less from the exit side of the first pass to the tension roll, and then the strip temperature is set at 100°C or more and 250°C or less between the exit side of the first pass and the tension roll. The strip temperature between 100° C. and 250° C. is set between 100° C. and 250° C. during rolling.

[Function] Figure 2 is a diagram showing the relationship between the temperature of a silicon steel plate and its brittle rupture rate. According to FIG. 2, it is recognized that the area ratio of brittle fracture surfaces decreases by increasing the strip temperature.

Moreover, FIG. 3 is a diagram showing the relationship between the St content and the incidence of plate breakage when a silicon steel plate is rolled by a conventional rolling method. According to this Figure 3, it is recognized that as the St content increases, the material becomes brittle, and the incidence of plate breakage increases.Especially when it contains 1.5% or more of Si, It is observed that the number of plate breaks increases significantly.

Figure 4 shows the strip temperature on the first pass entry side, the strip temperature between the first pass exit side and the tension roll, and the plate breakage when rolling a silicon steel plate containing 1.5% or more Si. FIG. In other words, if the strip temperature on the first pass entry side is less than 50°C, plate breakage will occur at the deflector roll etc. on the rolling machine entry side, and the strip temperature between the first pass exit side and the tension roll will decrease. When the temperature is lower than 100°C, it is recognized that plate breakage occurs at the tension roll portion.

Note that if the strip temperature exceeds 250° C., (i) an oxide film will be formed on the surface of the IJ tube, which will deteriorate the surface condition, which is undesirable.

Even after the second pass, if the plate thickness is large, the bending strain becomes large and the plate may break. For this reason, plate breakage can be prevented by rolling the strip at a temperature of 100°C or more and 250°C or less between the exit side of the subsequent lotus and the tension roll after the second pass. .

Therefore, according to the present invention, it is possible to prevent the occurrence of fracture and obtain a stable cold rolled state without deteriorating the surface state of the silicon steel sheet.

[Example] FIG. 1 is a layout diagram showing an example of rolling equipment to which the present invention is applied. The rolling mill 10 consists of three stands, and a tension roll 11 is provided between each stand. Further, on the entry side of the rolling mill 10, an unwinding machine 12. A shearing machine 13, a welding machine 14, a heat insulation looper 15, and a heat insulation panel 16 are provided, and a winder 17 is provided on the exit side of the rolling mill 10. here,
The rewind R12 needs to be an insulated reel depending on the coil temperature on the inlet side. The shearing machine 13 cuts off the defective shape portion of the coil end, and continues welding the coil end fi14.
This makes it completely weldable. The heat-retaining looper 15 stores strips so that the rolling state in the rolling mill 10 can be continued while the preceding coil and the succeeding coil are welded [14]. The heat retaining panel 16 is provided between the unwinding machine 12 and the inlet side of the heat retaining looper 15, the entire heat retaining looper 15, and from the exit side of the heat retaining looper 15 to the inlet side of the first stand of the rolling mill 10. The heat insulation panel 16 has, for example, 10
It is made of a steel plate structure using a heat insulating material such as glass wool with a thickness of 0.0 cm, and it is possible to reduce the temperature of the strip from the unwinding machine 12 to the entrance side of the rolling mill 10 by 2 to 3°C.

In the above-mentioned rolling equipment, in order to set the strip temperature on the first pass entry side to 50°C or more and 250°C or less, (a) an electric heater, steam and heat on the entry side of the heat retention looper 15 that can raise the temperature of the strip; A heating facility 18 using exchanged air or the like is provided, or b) unwinding a12.
Either the temperature of the coil charged into the coil is maintained at a high temperature by synchronization with the previous process, or (C) the coil heated to a predetermined temperature by a heating box or the like can be loaded into the unwinding machine 12. For example, if the heating box is used to set the initial temperature to 2.
In order to heat a coil at 0°C to 55°C, it is sufficient to hold the coil in an atmospheric gas with an average gas temperature of 160°C for 10 hours. When this is passed through an input side facility without heating equipment 18, the temperature drop from the unwinding machine 12 to the input side of the rolling mill 10 is 2 to 3°C, so the strip temperature at the input side of the rolling mill 10 is is 52-53°C.

In addition, in the above rolling equipment, the energy of the rolling process by the first scraper is effectively used, and the strip temperature between the first scraper exit side and the tension roll can be set at 100°C or more and 250°C or less. It is said that

That is, the strip temperature after finishing rolling in the first pass is determined by the temperature of the rolled material before rolling, the roll temperature, the plastic working heat value Qw of the strip in the roll bite, the friction heat value Qf between the roll and the strip, and the roll. is determined by the heat conduction between the strips. These relationships can be expressed numerically as follows. First, the heat conduction equation inside the rolled material is as shown in equation (1) below.

Further, the heat conduction equation inside the roll is as shown in equation (2) below.

Furthermore, assuming that there is no thermal resistance, the boundary conditions between the roll surface and the material surface are as shown in the following equations (3) and (4).

θ=U... (3) where U: Rolled material temperature θ: Roll temperature a: Temperature conductivity included: Thermal conductivity (however, the subscript S indicates the rolled material, R indicates the roll) CP: Rolled material temperature Specific heat γ: Density of the rolled material X: Distance from the center of the rolled material r: Distance from the roll center by 2 The formula is as follows.

Here, A: Work equivalent of heat α: Rate at which work is consumed as heat: Resistance to two-dimensional deformation of rolled material: Strain rate surge: Coefficient of friction between the roll and rolled material p: Roll surface pressure: Roll speed vS: Speed of the rolled material Therefore, using the rolled material temperature before rolling and the roll temperature as initial conditions, the above equations (3) and (4) can be expressed as the boundary line Jt1+
l ii Lne tl) -+7 hi barsu)
By solving the equation, it is possible to determine the strip temperature after rolling. When the rolling reduction ratio is increased, the deformation resistance k, strain rate a, roll surface pressure p, etc. of the rolled material increase, so that the strip temperature after rolling increases.

A specific example of the rolling conditions that allows the strip temperature from the first pass exit side to the tension roll to be set at 100° C. or more and 250° C. or less will be described below. That is, FIG. 5 shows the stripping speed when the input side stripping speed is 30 ml/minute, the roll temperature is 10°C, the input side stripping temperature is 50°C, and the range from the first pass exit side to the tension roll is air-cooled. FIG. 3 is a diagram showing the relationship between the rolling reduction rate in one pass and the strip temperature in the tension roll portion. According to this Fig. 7, the rolling reduction rate in the first pass is 3.
It is recognized that by setting the content to 1% or more, it is possible to increase the strip temperature in the tension roll portion to 100° C. or more.

Further, an example in which the plate thickness is thick is as follows. 1st
The strip temperature on the input side of the pass was 80°C, the rolling reduction rate of the first pass was 37t, the rolling reduction rate of the second pass was 40%, and the rolling reduction rate of the third pass was 30%, and the range from the exit side of each pass to the tension roll. When the area from the tension roll to the entrance side of each stand is water-cooled, the strip temperature from the exit side of the first pass to between the tension rolls is approximately 156°C, as shown in Figure 8. The temperature between the side and the tension roll is about 177°C, and the temperature between the third pass output side and the tension roll is about 164°C. In this case, the initial temperature of the roll is 70℃
The third pass exit speed of , stream, and b is 500 m/min. By rolling with these settings, the plate could be rolled without breaking.

Effects of the Invention As described above, the first aspect of the present invention is that in a method for cold rolling a silicon steel sheet containing 1.5% or more of Si, the strip temperature on the first pass entry side is set to 50°C or more and 250°C or more. The strip temperature between the first pass exit side and the tension roll is set at 100° C. or more and 250° C. or less for rolling.

Further, the second aspect of the present invention is a method for cold rolling a silicon steel sheet containing 1.5% or more of Si, in which the strip temperature on the first pass entry side is set to 50°C or more and 250°C or less, and the first pass Set the strip temperature between the exit side and the tension roll to 100°C or more and 250°C or less, and then set the strip temperature between the exit side and the tension roll in the second pass and subsequent passes to 100°C or more and 250°C or less. The rolling method was set to .

Therefore, it is possible to prevent the occurrence of fractures during rolling of silicon steel sheets and improve rolling efficiency and yield without any restrictions regarding the arrangement of rolling equipment or complicated equipment.

[Brief explanation of drawings]

Fig. 1 is a layout diagram showing an example of rolling equipment to which the present invention is applied, Fig. 2 is a diagram showing the relationship between plate temperature and brittle fracture rate of silicon steel plate, and Fig. 3 is a diagram showing the relationship between silicon steel plate and Si content. Fig. 4 is a graph showing the strip temperature range in which plate breakage does not occur, Fig. 5 is a graph showing the rolling reduction ratio of the first pass and the tension roll section after the first pass rolling. Diagram showing the relationship between strip temperature and strip temperature, Fig. 6(A), (
B) is a schematic diagram showing a conventional rolling equipment, FIG. 7 is a schematic diagram showing another conventional rolling equipment, and FIG. 8 is a diagram showing a specific application example of the present invention. 10... Rolling mill, 11... Tension roll, 18
...Heating equipment. Agent Patent Attorney Osamu Shiokawa Figure 2 Figure 3 Figure 4 Figure 1 Strip 3LFn ('' C) Figure 5 Rolling ratio of 1-V (required) Figure 8

Claims (2)

[Claims] (1) In a method for cold rolling silicon steel sheets containing 1.5% or more of Si, the strip temperature on the first pass entry side is set to 50%.
℃ or more and 250℃ or less, and the strip temperature between the first pass exit side and the tension roll is set to 100℃ or more and 250℃ or less.
A method for cold rolling a silicon steel sheet, comprising rolling at a temperature of 50°C or lower. (2) In a method for cold rolling silicon steel sheets containing 1.5% or more of Si, the strip temperature at the entrance of the first pass is set to 50%.
℃ or more and 250℃ or less, and the strip temperature between the first pass exit side and the tension roll is set to 100℃ or more and 250℃ or less.
Cooling of a silicon steel sheet characterized by rolling at a temperature of 50°C or less, and then setting the strip temperature between the exit side of the second pass and subsequent passes to a tension roll at 100°C or more and 250°C or less. Inter-rolling method.