Asymmetric rolling apparatus and rolling method

Abstract

According to the present disclosure, an asymmetric rolling apparatus comprises: a small-diameter work roll that comes into contact with one surface of a material to be rolled; and a large-diameter work roll that comes into contact with the other surface of the material to be rolled and has a larger diameter than the small-diameter work roll. The diameter of the small-diameter work roll is within 70-90 mm, and the diameter of the large-diameter work roll is within 2-5 times the diameter of the small-diameter work roll.

Description

Asymmetric rolling device and rolling method

[0001] The present disclosure relates to an asymmetric rolling apparatus and an asymmetric rolling method capable of improving the texture of a material.

[0002] In general, various asymmetric rolling methods are proposed for the purpose of reducing rolling load, improving rollability, and improving material texture. Representative asymmetric rolling methods include the unidirectional rolling method, the single drive method, the vertical asymmetric friction method, and the isoperipheral rolling method.

[0003] The dual-speed rolling method utilizes the speed difference between the upper and lower work rolls as an asymmetric factor, but increasing the rolling speed is difficult due to the occurrence of slip and chatter. Furthermore, commercialization is constrained by limitations on the vertical speed difference and the reduction of the asymmetric effect during lubricated rolling.

[0004] The single drive method utilizes unilateral drive as an asymmetric factor, but it has the disadvantage that it is difficult to apply pressure due to insufficient torque and the asymmetric effect is small.

[0005] The vertical asymmetric friction method uses friction between the upper and lower work rolls and the plate as an asymmetric factor, but it causes differences in product surface quality and presents difficulties in configuring equipment capable of separating upper and lower lubrication conditions during actual application.

[0006] The isoperipheral speed irregular rolling method achieves an asymmetric effect through the difference in diameter between the upper and lower work rolls, making it more feasible for actual commercialization than the previously mentioned asymmetric rolling methods. However, there is a challenge in that clear criteria for rolling conditions capable of inducing maximum shear deformation in the material have not yet been established.

[0007] One aspect of the present disclosure aims to provide an asymmetric rolling apparatus and a rolling method having upper and lower work roll diameters capable of ensuring productivity by applying maximum shear deformation during rolling.

[0008] The technical problems to be solved in this document are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this invention belongs from the description below.

[0009] According to an embodiment of the present disclosure, an asymmetric rolling device may be provided comprising a small-diameter work roll that contacts one side of a workpiece to be rolled and a large-diameter work roll that contacts the other side of the workpiece and has a larger diameter than the small-diameter work roll, wherein the diameter of the small-diameter work roll is within 70 to 90 mm and the diameter of the large-diameter work roll is within 2 to 5 times the diameter of the small-diameter work roll.

[0010] The above rolled material includes electrical steel sheets.

[0011] The above small diameter work roll may be located on the upper part of the rolled material, and the above large diameter work roll may be located on the lower part of the rolled material.

[0012] It includes a first roll set comprising the above-mentioned small-diameter work roll and one or more first support rolls positioned around the above-mentioned small-diameter work roll.

[0013] It includes a second roll set comprising the above-mentioned large-diameter work roll and one or more second support rolls arranged around the above-mentioned large-diameter work roll.

[0014] The above first roll set may be movable up and down.

[0015] The above first roll set can be provided in the form of a cluster mill.

[0016] The first roll set above further includes a cassette including the small diameter work roll.

[0017] In another aspect, according to one embodiment of the present disclosure, an asymmetric rolling device comprising a small diameter work roll and a large diameter work roll for rolling a workpiece with a thickness of 1.8 to 2.3 mm and a width of 1000 to 1300 mm to a thickness of 0.15 to 0.35 mm within 5 to 10 rolling passes can be provided, wherein the diameter of the small diameter work roll is within 70 to 90 mm and the diameter of the large diameter work roll is within 2 to 5 times the diameter of the small diameter work roll.

[0018] The above rolled material includes electrical steel sheets.

[0019] In another aspect, according to one embodiment of the present disclosure, an asymmetric rolling method can be provided by using an asymmetric rolling device comprising a small-diameter work roll with a diameter of 70 to 90 mm and a large-diameter work roll with a diameter of 2 to 5 times the diameter of the small-diameter work roll, and rolling a workpiece with a thickness of 1.8 to 2.3 mm and a width of 1000 to 1300 mm to a thickness of 0.15 to 0.35 mm based on a rolling pass.

[0020] The above rolling passes may be within 5 to 10 times.

[0021] The above rolled material includes electrical steel sheets.

[0022] When rolling the above-mentioned rolled material, the exit plate speed per rolling pass is 200 to 800 mpm, the rolling load is 400 to 900 tons, and the reduction rate per rolling pass may be 25 to 35%.

[0023] According to an embodiment of the present disclosure, productivity can be improved during asymmetric rolling of a material.

[0024] FIG. 1 is a schematic drawing illustrating an asymmetric rolling device according to one embodiment of the present disclosure.

[0025] FIG. 2 is a drawing for explaining the geometric structure of a small diameter work roll and a material according to one embodiment of the present disclosure.

[0026] Figure 3 is a diagram showing the maximum possible reduction amount for rolling according to the diameter and friction coefficient of the small-diameter work roll.

[0027] Figure 4 shows the minimum thickness of a material that can be rolled according to the diameter of the small-diameter work roll of the present disclosure.

[0028] FIG. 5 shows an asymmetric rolling apparatus including a small diameter work roll and a large diameter work roll according to one embodiment of the present disclosure.

[0029] FIG. 6 shows an asymmetric rolling apparatus including a small diameter work roll and a large diameter work roll according to another embodiment of the present disclosure.

[0030] The embodiments described in this specification are merely the most preferred embodiments of the present invention and do not represent all technical aspects of the present invention; therefore, it should be understood that various equivalents or modifications that can replace them at the time of filing this application are also included within the scope of the rights of the present invention.

[0031] Additionally, the same reference numerals or symbols presented in each drawing of the present disclosure represent parts or components that perform substantially the same function.

[0032] Furthermore, the terms used in this disclosure are for describing embodiments and are not intended to limit or restrict the disclosure. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this disclosure, terms such as “comprising” or “having” are intended to specify the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the disclosure, and do not preclude the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0033] Additionally, terms including ordinal numbers, such as “first,” “second,” etc., used in this disclosure may be used to describe various components, but said components are not limited by said terms, and said terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of this disclosure, the first component may be named the second component, and similarly, the second component may be named the first component. The term “and / or” includes a combination of a plurality of related described items or any of a plurality of related described items.

[0034] Furthermore, in this disclosure, the meaning of "identical" includes items that are similar in attributes or similar within a certain range. Additionally, "identical" means "substantially identical." The meaning of "substantially identical" should be understood as including within the scope of "identical" numerical values ​​that fall within the margin of error in manufacturing or differences that do not hold significance relative to a reference value.

[0035] In addition, terms such as "~part," "~unit," "~block," "~part," and "~module" may refer to a unit that processes at least one function or operation. For example, the above terms may refer to at least one piece of hardware such as an FPGA (field-programmable gate array) or ASIC (application specific integrated circuit), at least one piece of software stored in memory, or at least one process processed by a processor.

[0036] Singular expressions include plural expressions unless there is an obvious exception in the context.

[0037] Meanwhile, terms such as “front,” “rear,” “left,” and “right” used in the following description are defined based on the drawings, and the shape and position of each component are not limited by these terms.

[0038] Hereinafter, preferred embodiments according to the present disclosure will be described in detail with reference to the attached drawings.

[0039] FIG. 1 is a schematic drawing illustrating an asymmetric rolling device according to one embodiment of the present disclosure.

[0040] Referring to FIG. 1, the asymmetric rolling device (10) includes a small diameter work roll (20) and a large diameter work roll (30). The small diameter work roll (20) contacts one side of the material to be rolled (11), and the large diameter work roll (30) can contact the other side opposite to one side of the material to be rolled (11).

[0041] The asymmetric rolling device (10) is a device that rolls a workpiece (11) using a small-diameter work roll (20) and a large-diameter work roll (30) having different diameters. In the disclosed embodiment, a configuration is shown in which the small-diameter work roll (20) is positioned above the workpiece (11) and the large-diameter work roll (30) is positioned below the workpiece (11), but it is obvious that the small-diameter work roll (20) can be positioned below the workpiece (11).

[0042] When rolling a workpiece (11) by work rolls (20, 30) having different diameters, the shear stress acting on the upper and lower surfaces of the workpiece (11) acts differently from each other, thereby improving the texture of the material.

[0043] In order to apply maximum shear deformation to the rolled material (11), the asymmetric rolling device (10) may be configured such that the diameter of the small-diameter work roll (20) is within 70 to 90 mm, and the diameter of the large-diameter work roll (30) is within 2 to 5 times the diameter of the small-diameter work roll (20).

[0044] For example, when the diameter ratio of the small diameter work roll (20) and the large diameter work roll (30) is 1:2, the diameter of the large diameter work roll (30) can be 140 to 180 mm; when the diameter ratio is 1:3, the diameter of the large diameter work roll (30) can be 210 to 270 mm; when the diameter ratio is 1:4, the diameter of the large diameter work roll (30) can be 280 to 360 mm; and when the diameter ratio is 1:5, the diameter of the large diameter work roll (30) can be 350 to 450 mm. Here, if the diameter ratio exceeds 1:5, the size of the asymmetric rolling device (10) becomes excessively large, making actual production and operation difficult, and significantly increasing production costs, which reduces economic efficiency.

[0045] The material to be rolled (11) may include an electrical steel sheet. The material to be rolled (11) is a material with a high silicon content of 3% or more, which has high strength and a high possibility of sheet breakage due to brittleness. In order to ensure productivity while rolling such a material thinly, the diameter of the small-diameter work roll (20) may be provided within 70 to 90 mm.

[0046] In addition, in order to reduce the thickness of the material to be rolled (11) after rolling, the diameter of the small-diameter work roll (20) must be small. However, if the diameter of the small-diameter work roll (20) is smaller than 70 mm, the amount of reduction must be reduced because it is difficult for the material to be rolled to be fed between the upper and lower rolls of the rolling mill, which increases the number of rolling passes and reduces productivity. If it is larger than 90 mm, it is difficult to secure a thin sheet thickness. In the embodiment of the present disclosure, in order to secure a rolling thickness of 0.15 to 0.35 mm, which is the thickness of the material to be rolled (11) after rolling, the diameter of the small-diameter work roll (20) may be provided within 70 to 90 mm.

[0047] The asymmetric rolling device (10) may be provided as a reversible rolling device. The asymmetric rolling device (10) can be achieved in 5 to 10 rolling passes when rolling a workpiece (11) with a thickness of 1.8 to 2.3 mm and a width of 1000 to 1300 mm to a final thickness of 0.15 to 0.35 mm. At this time, the output plate speed per rolling pass is 200 to 800 mpm, the rolling load is 400 to 900 tons, and the reduction rate per rolling pass is 25 to 35%. That is, when the diameter of the small-diameter work roll (20) is smaller than 70mm, the amount of reduction decreases and the number of rolling passes increases, and when the diameter of the small-diameter work roll (20) is larger than 90mm, it is difficult to secure a final thin sheet thickness of 0.15~0.35mm, but when the diameter of the small-diameter work roll (20) is within 70~90mm and the diameter of the large-diameter work roll (30) is within 2~5 times the diameter of the small-diameter work roll (20), a final thickness of 0.15~0.35mm after rolling can be secured with 5~10 rolling passes.

[0048] FIG. 2 is a drawing for explaining the geometric structure of a small diameter work roll and a material according to one embodiment of the present disclosure.

[0049] Referring to FIG. 2, the thickness of the workpiece (11) is reduced from H1 to H2 using a small-diameter work roll (20) having radius R, and the friction coefficient between the workpiece (11) and the small-diameter work roll (20) is indicated as μ. That is, the inlet thickness (H1) of the workpiece (11) is being rolled to the outlet thickness (H2) by the small-diameter work roll (20), and the friction coefficient μ between the workpiece (11) and the surface of the small-diameter work roll (20) is also indicated.

[0050] In order for smooth rolling of the material to be rolled (11) by the small diameter work roll (20), mathematical formula 1 must be satisfied.

[0051] [Mathematical Formula 1]

[0052]

[0053] Here, it can be seen that in order to increase the reduction amount (H1-H2), the friction coefficient (μ) must be increased or the diameter of the small-diameter work roll (20) must be enlarged. Since high productivity is required in actual industrial rolling mills, the reduction amount per pass must be large and the rolling speed must be fast. Therefore, in terms of rolling efficiency, it is advantageous to have a large diameter of the small-diameter work roll (20).

[0054] Figure 3 is a diagram showing the maximum possible reduction amount for rolling according to the diameter and friction coefficient of the small-diameter work roll.

[0055] Referring to FIG. 3, as the diameter of the small-diameter work roll (20) increases from 40 mm to 100 mm, the reduction amount (H1-H2) shows a gradual increasing trend. At this time, the friction coefficient is closely related to the change in the maximum reduction amount, and it can be seen that the range of variation in the maximum reduction amount according to the change in the diameter of the small-diameter work roll (20) is greater when the friction coefficient (μ) is 0.1.

[0056] When rolling with a reduction rate of 25~35% per rolling pass, the reduction amount (H1-H2) is greatest in the first pass. This is because the strength is low before the material is work-hardened, and the friction coefficient acts significantly due to the low rolling speed. Therefore, even when using a small-diameter work roll (20) with a diameter of 80 mm, a reduction amount of 0.7 mm can be achieved. In other words, because the amount of rolling oil entering the roll is reduced due to the low speed, the friction coefficient increases, and as a result, rolling with a reduction amount of 0.7 mm is possible even with a small-diameter work roll (20) with a diameter of 80 mm.

[0057] From the second pass onwards, the surface roughness of the plate becomes smaller and the plate becomes flatter than the material entering the first pass, so the rolling speed can be increased and the coefficient of friction is reduced. Therefore, as the number of passes increases, the work-hardened workpiece can be rolled with the same small-diameter roll while reducing the reduction amount.

[0058] Mathematical formula 2 is the minimum thickness (h) of the plate that can be rolled due to roll flattening of the small diameter work roll (20) during rolling. min It is a formula that defines ).

[0059] [Mathematical Formula 2]

[0060]

[0061] Here, D represents the diameter of the work roll, μ is the coefficient of friction, k is the deformation resistance (yield strength) of the material, and E is the elastic modulus (Young's modulus) of the work roll.

[0062] From mathematical formula 2, it can be seen that in order to reduce the plate thickness, the diameter and friction coefficient of the small-diameter work roll (20) must be reduced. However, it is important to ensure that the thickness of the exit side is reduced while minimizing the number of rolling passes in order to secure rolling productivity. That is, if the diameter of the small-diameter work roll (20) becomes too small, the amount of reduction decreases and the number of passes increases, and if the diameter of the small-diameter work roll (20) becomes too large, it becomes difficult to achieve the final thin plate thickness.

[0063] Figure 4 shows the minimum thickness of a material that can be rolled according to the diameter of the small-diameter work roll of the present disclosure.

[0064] Referring to FIG. 4, the minimum thickness that can be rolled is shown when a material with a thickness of 0.5 mm is rolled to 1 mm using a compression cylinder in a kissing (initial contact state) state with small-diameter work rolls (20) of diameters of 80 mm, 160 mm, 250 mm, and 390 mm, and the roll gap is closed, i.e., the gap between the work rolls is narrowed. It can be seen that when the roll gap is closed with a small-diameter work roll (20) of diameter 390 mm, the load increases and the roll flattening amount increases, but the output plate thickness is not rolled to 0.422 mm or less. On the other hand, when using a small-diameter work roll (20) of diameter 80 mm, the output plate thickness can be rolled to 0.105 mm.

[0065] Accordingly, in an asymmetric rolling device (10) including a small-diameter work roll (20) and a large-diameter work roll (30) shown in FIG. 1, the diameter of the small-diameter work roll (20) capable of rolling a workpiece (11) of electrical steel sheet material with a thickness of 1.8 to 2.3 mm and a width of 1000 to 1300 mm to a final thickness of 0.15 to 0.35 mm within a range of 5 to 10 rolling passes is 70 to 90 mm, and the diameter of the large-diameter work roll (30) can be provided within 2 to 5 times the diameter of the small-diameter work roll (20).

[0066] FIG. 5 shows an asymmetric rolling apparatus including a small diameter work roll and a large diameter work roll according to one embodiment of the present disclosure.

[0067] The asymmetric rolling device (10) shown in FIG. 5 can be composed of a 12-stage rolling mill.

[0068] This asymmetric rolling device (10) includes a small diameter work roll (20) and a large diameter work roll (30) having different diameters, and the small diameter work roll (20) may be positioned above the material to be rolled (11), and the large diameter work roll (30) may be positioned below the material to be rolled (11).

[0069] According to one embodiment, the asymmetric rolling device (10) may include a first roll set (40) including a small-diameter work roll (20) and a second roll set (50) including a large-diameter work roll (30). The first roll set (40) and the second roll set (50) may each include one or more support rolls. One or more support rolls may be positioned around the work rolls (20, 30) to prevent shape deformation of the work rolls (20, 30). One or more support rolls may be positioned on the outer surface of the work rolls. One or more support rolls may be positioned to contact the outer surface of the work rolls (20, 30) to prevent bending deformation of the work rolls (20, 30). One or more support rolls may be positioned to be kinetically connected to the work rolls (20, 30).

[0070] According to one embodiment, the first roll set (40) may be positioned above the rolling path of the workpiece (11). During rolling, the first roll set (40) may apply pressure to the upper surface of the workpiece (11).

[0071] According to one embodiment, the second roll set (50) can apply pressure to the lower surface of the workpiece (11). The second roll set (50) can be positioned below the rolling path of the workpiece (11).

[0072] According to one embodiment, one or more first support rolls of the first roll set (40) may be positioned around the small diameter work roll (20). The one or more first support rolls may include two primary intermediate rolls (41) supporting the small diameter work roll (20), three secondary intermediate rolls (42) supporting the primary intermediate rolls (41), and four backup rolls (43) supporting the three secondary intermediate rolls (42).

[0073] According to one embodiment, one or more second support rolls of the second roll set (50) may include one backup roll (51) that supports the large diameter work roll (30).

[0074] According to one embodiment, the first roll set (40) can move up and down. The first roll set (40) can be operatively connected to a movement mechanism. The movement mechanism can provide power to move the first roll set (40) up and down. The gap between the first roll set (40) and the second roll set (50) can be adjusted by the movement mechanism. The gap is the distance between the small diameter work roll (20) of the first roll set (40) and the large diameter work roll (30) of the second roll set (50). The distance between the small diameter work roll (20) and the large diameter work roll (30) can be determined as the shortest distance between the outer surface of the large diameter work roll (30) and the outer surface of the small diameter work roll (20).

[0075] According to one embodiment, the first roll set (40) moves from the top to the bottom, and the compression force applied to the workpiece (11) can be increased. As the compression force increases, the amount of compression increases. While the first roll set (40) is moving, the second roll set (50) can be maintained in a fixed position. By maintaining the second roll set (50) in a fixed position, the stability of the equipment can be increased. Since the second roll set (50) also serves as a movement path for the workpiece (11), it is preferable to maintain the installed position rather than move up and down.

[0076] According to one embodiment, the small diameter work roll (20) is susceptible to bending deformation compared to the large diameter work roll (30). Accordingly, the small diameter work roll (20) can be operatively connected to one or more support rolls in the form of a cluster mill.

[0077] According to one embodiment, one or more first support rolls may be positioned around a small-diameter work roll (20). One or more first support rolls may be positioned so that their outer surfaces are in contact with the small-diameter work roll (20). As the small-diameter work roll (20) is supported by one or more first support rolls, bending deformation may be minimized.

[0078] FIG. 6 shows an asymmetric rolling device including a small diameter work roll and a large diameter work roll according to another embodiment of the present disclosure. In the following, the same reference numerals are assigned to components having the same function, and a detailed description is omitted.

[0079] The asymmetric rolling device (10) shown in FIG. 6 can be configured in the form of a 5-stage rolling mill.

[0080] This asymmetric rolling device (10) may include a first roll set (40) including a small diameter work roll (20) and a second roll set (50) including a large diameter work roll (30).

[0081] According to one embodiment, the first roll set (40) may include a cassette (60) including a small diameter work roll (20) and one or more first support rolls. The cassette (60) may be detachably mounted from the rolling device to shorten roll replacement time and facilitate maintenance. One or more first support rolls may include one backup roll (43).

[0082] According to one embodiment, the cassette (60) may include a small diameter work roll (20) and one or more first support rolls disposed around the small diameter work roll (20).

[0083] According to one embodiment, one or more first support rolls provided in the cassette (60) may include one intermediate roll (61) that supports a small diameter work roll (20).

[0084] According to one embodiment, one or more first support rolls provided in a cassette (60) may include one intermediate roll (61) supporting the upper part of a small-diameter work roll (20) and six intermediate rolls (62) supporting the side of a small-diameter work roll (20). Here, the six intermediate rolls (62) supporting the side of a small-diameter work roll (20) may have a smaller diameter than the one intermediate roll (61) supporting the upper part of a small-diameter work roll (20).

[0085] Although the technical concept of the present invention has been explained above through specific embodiments, the scope of the present invention is not limited to these embodiments. Various embodiments that can be modified or varied by those skilled in the art within the scope that does not deviate from the gist of the technical concept of the present invention as specified in the claims shall also be considered to fall within the scope of the present invention.

Claims

1. A small-diameter work roll in contact with one side of the rolled material; and It includes a large-diameter work roll that contacts the other surface of the above-mentioned rolled material and has a diameter larger than that of the small-diameter work roll; The diameter of the above-mentioned small-diameter work roll is within 70 to 90 mm, and An asymmetric rolling device in which the diameter of the above-mentioned large-diameter work roll is within 2 to 5 times the diameter of the above-mentioned small-diameter work roll.

2. In Paragraph 1, The above-mentioned rolled material is an asymmetric rolling device including an electrical steel sheet.

3. In Paragraph 1, An asymmetric rolling device in which the small diameter work roll is located above the workpiece and the large diameter work roll is located below the workpiece.

4. In Paragraph 1, An asymmetric rolling device comprising a first roll set including the above-mentioned small-diameter work roll and one or more first support rolls positioned around the above-mentioned small-diameter work roll.

5. In Paragraph 4, An asymmetric rolling device comprising a large-diameter work roll and a second roll set comprising one or more second support rolls arranged around the large-diameter work roll.

6. In Paragraph 4, The above first roll set is an asymmetric rolling device capable of moving up and down.

7. In Paragraph 4, The above first roll set is an asymmetric rolling device provided in the form of a cluster mill.

8. In Paragraph 4, The above first roll set is an asymmetric rolling device further comprising a cassette including the above small diameter work roll.

9. An asymmetric rolling device comprising a small-diameter work roll and a large-diameter work roll for rolling a workpiece with a thickness of 1.8~2.3mm and a width of 1000~1300mm to a thickness of 0.15~0.35mm within 5~10 rolling passes, The diameter of the above-mentioned small-diameter work roll is within 70 to 90 mm, and An asymmetric rolling device in which the diameter of the above-mentioned large-diameter work roll is within 2 to 5 times the diameter of the above-mentioned small-diameter work roll.

10. In Paragraph 9, The above-mentioned rolled material is an asymmetric rolling device including an electrical steel sheet.

11. An asymmetric rolling device comprising a small-diameter work roll with a diameter of 70 to 90 mm and a large-diameter work roll with a diameter of 2 to 5 times the diameter of the small-diameter work roll, and An asymmetric rolling method for rolling a workpiece with a thickness of 1.8 to 2.3 mm and a width of 1000 to 1300 mm to a thickness of 0.15 to 0.35 mm based on a rolling pass.

12. In Paragraph 11, The above rolling pass is an asymmetric rolling method within 5 to 10 passes.

13. In Paragraph 12, The above-mentioned rolled material is an asymmetric rolling method including an electrical steel sheet.

14. In Paragraph 12, An asymmetric rolling method in which, when rolling the above-mentioned workpiece, the exit plate speed per rolling pass is 200 to 800 mpm, the rolling load is 400 to 900 tons, and the reduction rate per rolling pass is 25 to 35%.

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