Method for trimming side portion of electric steel plate

Abstract

The disclosed side trimming method for a high-silicon steel sheet comprises: a heat treatment step of heating the high-silicon steel sheet to a temperature higher than a preset cutting temperature and then cooling it to the cutting temperature; and a side cutting step of cutting the end so as to remove a crack formed at the end in the width direction of the high-silicon steel sheet at the cutting temperature.

Description

Technology Field

[0001] The present invention relates to a side trimming method for high-silicon steel sheets, and more specifically, to a side trimming method for high-silicon steel sheets that reduces energy consumption and operating costs. Background Technology

[0003] High-silicon steel sheets containing a high concentration of silicon (Si) have excellent magnetic properties and are used, for example, as core materials for motors or generators. Accordingly, high-silicon steel sheets are also referred to as electrical steel sheets. However, high-silicon steel sheets have high brittleness, making them prone to cracking at the edges in the width direction during the rolling process used to process them into thin sheets.

[0004] The background technology of the present invention is disclosed in Korean Patent Publication No. 10-2015-0071169 (published June 26, 2015; Title of Invention: Device and Method for Side Trimming of High-Strength Steel). The problem to be solved

[0006] According to one embodiment of the present invention, the purpose is to provide a side trimming method for high-silicon steel sheets in which the process is simplified, productivity is improved, and energy consumption and operating costs are reduced. means of solving the problem

[0008] A side trimming method for a high-silicon steel sheet according to the present invention is characterized by comprising: a heat treatment step of heating the high-silicon steel sheet to a temperature higher than a preset cutting temperature and then cooling it to the cutting temperature; and a side cutting step of cutting the end so as to remove a crack formed at the end in the width direction of the high-silicon steel sheet at the cutting temperature.

[0009] The heat treatment step may include the step of continuously moving the high silicon steel plate in one direction, heating the entire area in the width direction of the high silicon steel plate to a temperature higher than the cutting temperature, and then cooling it to the cutting temperature.

[0010] The above cutting temperature may be 100 to 200℃.

[0011] The side trimming method of a high-silicon steel sheet according to the present invention may further include a hot rolling step of manufacturing the high-silicon steel sheet by hot rolling prior to the heat treatment step.

[0012] The side trimming method of a high-silicon steel sheet according to the present invention may further include a cold rolling step of cold rolling the high-silicon steel sheet after the side cutting step.

[0013] The side trimming method of a high-silicon steel sheet according to the present invention may further include a post-cold rolling annealing step for removing internal stress of the high-silicon steel sheet after the cold rolling step.

[0014] The side trimming method of a high-silicon steel plate according to the present invention may further include a pickling step in which the high-silicon steel plate is immersed in an acidic solution after the side cutting step to smooth the surface of the high-silicon steel plate.

[0015] The side trimming method of a high-silicon steel sheet according to the present invention may further include a shot blast step between the side cutting step and the pickling step, wherein the surface of the high-silicon steel sheet is struck with fine particles to remove impurities from the surface of the high-silicon steel sheet.

[0016] The above side cutting step may include at least one step among a mechanical cutting step of cutting the end in the width direction of the high silicon steel plate by applying shear force using a knife, and a laser cutting step of cutting the end in the width direction of the high silicon steel plate using thermal energy of a laser. Effects of the invention

[0018] According to the side trimming method of a high-silicon steel sheet of the present invention, the process is simplified, the productivity of the high-silicon steel sheet is improved, the energy input for manufacturing the high-silicon steel sheet is reduced, and the operating cost is also reduced. Brief explanation of the drawing

[0020] Figure 1 is a plan view showing a high-silicon steel plate with cracks formed at both ends in the width direction. FIG. 2 is a block diagram showing a side trimming method of a high-silicon steel sheet according to one embodiment of the present invention. FIG. 3 is a perspective view illustrating an example of a side trimmer performing the side cutting step of FIG. 2. Fig. 4 is a perspective view of Fig. 3 cut along IV-IV. Specific details for implementing the invention

[0021] Hereinafter, a side trimming method for a high-silicon steel sheet according to the present invention will be described in detail with reference to the attached drawings. The terminology used in this specification is used to appropriately express preferred embodiments of the present invention, and may vary depending on the intent of the user or operator or the conventions of the field to which the present invention belongs. Therefore, the definitions of these terms should be based on the content throughout this specification.

[0022] FIG. 1 is a plan view illustrating a high-silicon steel plate with cracks formed at both ends in the width direction, and FIG. 2 is a block diagram illustrating a side trimming method of a high-silicon steel plate according to an embodiment of the present invention. Referring to FIG. 1 and FIG. 2, the side trimming method of a high-silicon steel plate according to an embodiment of the present invention includes a heat treatment step (S200) and a side cutting step (S300).

[0023] High silicon steel sheet (1) is also called electrical steel sheet or electronic steel sheet, and has excellent electromagnetic properties because it has a higher silicon (Si) content than ordinary steel sheet. High silicon steel sheet (1) is used as a material for the core of, for example, transformers, generators, and motors, and has lower iron loss than ordinary steel sheet.

[0024] High silicon steel plate (1) has high silicon content, which causes brittleness, and many cracks (4) may occur at both ends (3) in the width direction (W). The side cutting step (S300) is a step of cutting off both ends (3) of the high silicon steel plate (1) to prevent damage to the high silicon steel plate (1) caused by the spread and deepening of cracks (4) and to increase the marketability of the high silicon steel plate (1).

[0025] The heat treatment step (S200) is a step of heating the high silicon steel plate (1) to a temperature higher than a preset cutting temperature and then cooling it to the cutting temperature. Before cutting the high silicon steel plate (1), it is heated to the cutting temperature to soften the structure and obtain a clean cut surface. The cutting temperature may be, for example, 100 to 200°C.

[0026] In the heat treatment step (S200), the temperature higher than the cutting temperature may be, for example, 900 to 1100°C. The heat treatment step (S200) may include a preheating step, a step of heating to a temperature higher than the aforementioned cutting temperature, a step of maintaining the high temperature for a certain period of time, a step of cooling slowly to lower the temperature, and a step of cooling rapidly to lower the temperature to the cutting temperature.

[0027] The electromagnetic properties of the high silicon steel plate (1) can be further improved through the heat treatment step (S200). For example, the iron loss can be further lowered and the magnetic flux density can be increased through the heat treatment step (S200). The side cutting step (S300) is a step of cutting the ends (3) so that cracks (4) formed on both ends (3) of the high silicon steel plate (1) at the aforementioned cutting temperature are removed.

[0028] A side trimming method for a high silicon steel sheet according to one embodiment of the present invention may further include a hot rolling step (S100), a shot blasting step (S400), a pickling step (S500), a cold rolling step (S600), and an annealing step (S700) after cold rolling.

[0029] The hot rolling step (S100) is performed prior to the heat treatment step (S200) and is a step for manufacturing a high silicon steel plate (1) by hot rolling. In the hot rolling, a slab (not shown) manufactured by a continuous casting process is passed between one or more pairs of rolling rollers at a material recrystallization temperature of 1000°C or higher to manufacture a high silicon steel plate (1).

[0030] The heat treatment step (S200) may include a step of continuously moving the high-silicon steel plate (1) manufactured in the hot rolling step (S100) in one direction without interruption, heating the entire area in the width direction (W) of the high-silicon steel plate (1) to a temperature higher than the cutting temperature, and then cooling it to the cutting temperature.

[0031] The high-silicon steel sheet (1) manufactured in the hot rolling step (S100) can be stored and transported in a coiled state. Then, prior to being fed into the heat treatment step (S200) and the side cutting step (S300), the high-silicon steel sheet (1) wound in a coiled state is continuously supplied by unwinding the coil flat.

[0032] In order for the hot-rolled high-silicon steel plate (1) to be continuously fed into the heat treatment step (S200) and the side cutting step (S300) without interruption, the longitudinal (L) rear end of the high-silicon steel plate (1) into which one coil supplied first is unwound and fed, and the longitudinal (L) front end of the high-silicon steel plate (1) into which another coil supplied later is unwound and fed can be welded.

[0033] FIG. 3 is a perspective view illustrating an example of a side trimmer performing the side cutting step of FIG. 2, and FIG. 4 is a perspective view of FIG. 3 cut along IV-IV. Referring to FIG. 1 to 4, the side cutting step (S300) may include at least one step among a mechanical cutting step of cutting the end (3) of a high silicon steel plate (1) by applying shear force using a knife (35, 45), and a laser cutting step of cutting the end (3) of a high silicon steel plate (1) with thermal energy of a laser (L).

[0034] As a specific example, the side cutting step (S300) can be performed by a side trimmer. The side trimmer may include a frame (21), an upper knife (35), a lower knife (45), an upper laser irradiator (50), and a lower laser irradiator (60). The frame (21) can rotatably support the upper knife (35) and the lower knife (45).

[0035] FIGS. 3 and 4 only show a configuration in which one end (3) of the two sides of the high silicon steel plate (1) is cut and removed along a first cutting line (OL1), and a configuration in which the other end (3) of the high silicon steel plate (1) is cut and removed along a second cutting line (OL2) is not shown. However, for convenience of explanation and illustration, the side trimmer may further include a configuration in which the other end (3) of the two sides of the high silicon steel plate (1) is cut and removed along a second cutting line (OL2).

[0036] The upper knife (35) and the lower knife (45) are in the form of discs and can be rotatably supported on the frame (21) by the upper rotation axis (31) and the lower rotation axis (41), respectively. The upper knife (35) and the lower knife (45) are arranged such that a horizontal clearance and a vertical clearance of a certain length are formed between them. The horizontal clearance refers to a gap in which the upper knife (35) and the lower knife (45) are spaced apart in the width direction of the high silicon steel plate (1). The vertical clearance refers to a lap in which the upper knife (35) and the lower knife (45) overlap each other in the vertical direction.

[0037] The upper knife (35) and lower knife (45) are not rotated by the driving force of the motor, but can be rotated by the conveying force of the high silicon steel plate (1) moving in the direction of the arrow. As the high silicon steel plate (1) moves between the upper knife (35) and the lower knife (45) in the direction of the arrow, the end (3) is cut along the cutting line (OL1, OL2) by shearing and tearing by the upper knife (35) and the lower knife (45), leaving only the central part (2) between the two end parts (3) and proceeding to the next step.

[0038] The upper laser irradiator (50) and lower laser irradiator (60) provided in the side trimmer shown in FIGS. 3 and 4 can be installed to form an elongated groove along the cutting lines (OL1, OL2) on the upper and lower sides of the high silicon steel plate (1) so that mechanical cutting of the high silicon steel plate (1) using the upper knife (35) and lower knife (45) proceeds without defects and has a clean cut surface.

[0039] However, if the laser output is increased, the end (3) may be cut by only the laser (L) irradiation of the upper laser irradiator (50) and the lower laser irradiator (60). In this case, the side trimmer may not be equipped with an upper knife (35) and a lower knife (45) for cutting the end (3) of the high silicon steel plate (1) by a mechanical method.

[0040] Referring again to FIGS. 1 and FIGS. 2, the shot blasting step (S400) is a step of removing impurities from the surface of the high silicon steel plate (1) by striking the surface of the high silicon steel plate (1) with fine particles after the side cutting step (S300).

[0041] To elaborate, shot blasting is a process of removing foreign substances, corrosion, coatings, etc. remaining on the surface of a high-silicon steel plate (1) by spraying fine particles of metal or non-metal, such as shot or grit, at a high speed of 60 to 100 m / s. Through shot blasting, the appearance quality of the high-silicon steel plate (1) can be improved, and if a coating is subsequently formed on the surface of the high-silicon steel plate (1), the adhesion of the coating can be increased. Since the cycle time can be significantly reduced compared to sand blasting using sand, productivity can also be improved.

[0042] The pickling step (S500) is a step of smoothing the surface of a high-silicon steel plate (1) by immersing the high-silicon steel plate (1), from which the end (3) has been removed in the side cutting step (S200), in an acidic solution such as an aqueous hydrochloric acid solution. Through the pickling step (S500), the oxide film on the surface of the high-silicon steel plate (1) can be removed. By performing a shot blasting step (S400) prior to the pickling step (S500), the effect of the pickling step (S500) is enhanced and the surface of the high-silicon steel plate (1) can be made smoother.

[0043] The cold rolling step (S600) is a step of cold rolling the high silicon steel plate (1) after the pickling step (S500) so that the thickness of the high silicon steel plate (1) is reduced. Cold rolling is a step of producing a steel plate thinner than the steel plate formed by hot rolling by passing the steel plate produced by hot rolling between one or more pairs of rolling rollers. The temperature condition for cold rolling is a temperature lower than the temperature condition for hot rolling, for example, 50 to 350°C.

[0044] The annealing step after cold rolling (S700) is a step of performing annealing to remove internal stress of the high silicon steel plate (1) after the cold rolling step (S600). The annealing step may be performed to relieve stress accumulated inside the high silicon steel plate (1) due to machining such as the side cutting step (S300) and the cold rolling step (S600), to improve magnetic properties, and to restore the physical and mechanical properties of the high silicon steel plate (1) to the state before machining. Magnetic properties that can be improved in this step may include, for example, a reduction in iron loss and an increase in magnetic flux density.

[0045] Meanwhile, between the pickling step (S500) and the cold rolling step (S600), a step of inspecting for defects in the high silicon steel plate (1) from which the end (3) has been removed and re-winding the high silicon steel plate (1) into a coil shape may be further included. The high silicon steel plate (1) re-winding into a coil shape in this way can be transported to a plant for cold rolling treatment.

[0046] According to the side trimming method of the high silicon steel plate described above, the process is simplified, the productivity of the high silicon steel plate (1) is improved, the energy required to produce the high silicon steel plate (1) is reduced, and the operating cost is also reduced.

[0047] To elaborate, as a preliminary step for cutting and removing the end (3) of the hot-rolled high-silicon steel plate (1), the process of heating the end (3) of the high-silicon steel plate (1), the process of annealing the high-silicon steel plate (1) from which the end (3) has been removed prior to cold rolling, and the process of cooling the annealed high-silicon steel plate (1) with cooling water can be omitted, thereby improving the productivity of the high-silicon steel plate (1), saving energy, and reducing the operating cost.

[0048] The present invention has been described with reference to the embodiments illustrated in the drawings, but this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Accordingly, the true scope of protection of the present invention should be determined by the appended claims. Explanation of the symbols

[0050] 1: High silicon steel sheet 3: End 4: Crack 21: Frame 35: Upper knife 45: Lower knife 50: Upper laser irradiator 60: Lower laser irradiator

Claims

Claim 1 A method for side trimming an electrical steel sheet, comprising: a heat treatment step of heating the electrical steel sheet to a temperature higher than a preset cutting temperature and then cooling it to the cutting temperature; and a side cutting step of cutting the end so as to remove a crack formed at the end in the width direction of the electrical steel sheet at the cutting temperature; wherein the heat treatment step is performed prior to cutting the electrical steel sheet, and the heat treatment step comprises a step of continuously moving the electrical steel sheet in one direction and heating the entire area in the width direction of the electrical steel sheet to a temperature higher than the cutting temperature and then cooling it to the cutting temperature. Claim 2 delete Claim 3 A side trimming method for an electrical steel sheet according to claim 1, characterized in that the cutting temperature is 100 to 200℃. Claim 4 A side trimming method for an electrical steel sheet according to claim 1, further comprising a hot rolling step of manufacturing the electrical steel sheet by hot rolling prior to the heat treatment step. Claim 5 A side trimming method for an electrical steel sheet, characterized by further including a cold rolling step of cold rolling the electrical steel sheet after the side cutting step in claim 1. Claim 6 A side trimming method for an electrical steel sheet according to claim 5, further comprising a post-cold rolling annealing step for removing internal stress of the electrical steel sheet after the cold rolling step. Claim 7 A method for side trimming an electrical steel sheet according to claim 1, further comprising a pickling step in which the electrical steel sheet is immersed in an acidic solution after the side cutting step to smooth the surface of the electrical steel sheet. Claim 8 A side trimming method for an electrical steel sheet according to claim 7, further comprising a shot blast step between the side cutting step and the pickling step, wherein the surface of the electrical steel sheet is struck with fine particles to remove impurities from the surface of the electrical steel sheet. Claim 9 A method for side trimming of an electrical steel sheet according to claim 1, wherein the side cutting step comprises at least one step among a mechanical cutting step of cutting the end in the width direction of the electrical steel sheet by applying shear force using a knife, and a laser cutting step of cutting the end in the width direction of the electrical steel sheet using thermal energy of a laser.

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