Method for temper rolling a metal strip, temper rolling mill for a metal strip, and method for manufacturing a metal strip.
The temper rolling method with precise work roll settings and pressure adjustments in a four-stage rolling mill addresses edge mark issues, improving productivity and reducing costs by maintaining surface quality.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- JFE STEEL CORP
- Filing Date
- 2024-10-25
- Publication Date
- 2026-07-22
AI Technical Summary
Existing rolling mills face issues with edge mark transfer to metal strips due to uneven work roll wear, leading to reduced productivity, increased costs, and downtime, which conventional methods like rolling from wide to narrow strips or using dummy materials fail to adequately address, especially in mills lacking intermediate rolls or blasting devices.
A temper rolling method using a four-stage rolling mill with specific work roll roughness and crown settings, along with adjustable pressure loads, to suppress edge marks while maintaining surface roughness, applicable to both four-stage and six-stage mills.
The method effectively suppresses edge marks and maintains appropriate surface roughness, enhancing productivity and reducing production costs by minimizing roll changes and downtime.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a method for temper rolling a metal strip, a temper rolling mill for a metal strip, and a method for manufacturing a metal strip.
Background Art
[0002] Various types of rolling mills have been put into practical use as rolling mills used for cold rolling and temper rolling of metal strips. As such a rolling mill, a four-high rolling mill having a pair of work rolls for pressing a rolling target and a pair of backup rolls for supporting the work rolls, a six-high rolling mill having intermediate rolls in addition to the work rolls and backup rolls, etc. are generally used.
[0003] In such a rolling mill, when a metal strip of the same width is rolled for a long time, the edge portions of the work rolls are unevenly worn due to contact with the metal strip. Such uneven wear of the work roll is also referred to as, for example, an edge mark.
[0004] When rolling a metal strip having a width wider than the length between edge marks using a work roll with edge marks, there is a problem that the edge marks are transferred to the surface of the metal strip and the appearance of the product becomes inappropriate.
[0005] The roughness of the work roll is directly related to the appearance of the surface of the product. Therefore, the work roll is replaced in a short period from the start of rolling until its surface roughness decreases. The replacement of the work roll is relatively easy and can be replaced in a short time. Therefore, the influence on the production capacity of the product due to the replacement of the work roll is small.
[0006] Incidentally, when edge marks appear on a work roll, these marks are also transferred to the backup roll that is in contact with the work roll. Once edge marks are transferred to the backup roll, they will be transferred from the backup roll to the work roll even if the work roll is replaced. Therefore, when edge marks form on a work roll, the backup roll also needs to be replaced. Replacing the backup roll requires a long downtime of the production line, which leads to a decrease in production capacity.
[0007] Therefore, to prevent edge marks from being transferred to the metal strip, for example, the metal strip is rolled from wider strips to progressively narrower ones. When the rolling of the narrowest metal strip is completed, the work rolls are replaced, and the backup rolls are maintained or replaced. In addition, edge marks are removed from the work rolls by adjusting the pressure of a dummy material with a dull roll.
[0008] However, simply rolling a metal strip from a wide strip to a narrower one presents a problem of reduced productivity when changing the work rolls and backup rolls. Furthermore, the change of work rolls and backup rolls results in unpressed metal strips, requiring additional processes and increasing production costs.
[0009] Furthermore, the method of regulating pressure using dummy material with dull rolls has the problem of increasing manufacturing costs due to the use of dummy material. In addition, the production line must be slowed down when replacing with dull rolls, which reduces productivity.
[0010] As a method to improve the above-mentioned problems, for example, Patent Document 1 describes a method of preventing edge marks when rolling a metal strip using a multi-layer rolling mill by reciprocating the intermediate rolls in the direction of the roll axis during rolling.
[0011] Furthermore, in Patent Document 2, a metal strip is rolled from a wide metal strip to a gradually narrower metal strip, and when the rolling of the narrowest metal strip is completed, a high-roughness material is rolled.
[0012] Furthermore, in Patent Document 3, the surface portion of the rolling roll is blasted with shot particles or grit. [Prior art documents] [Patent Documents]
[0013] [Patent Document 1] International Publication No. 2019 / 181832 [Patent Document 2] Japanese Patent Application Publication No. 9-122716 [Patent Document 3] Japanese Patent Application Publication No. 3-5007 [Overview of the project] [Problems that the invention aims to solve]
[0014] However, in the method described in Patent Document 1, when the metal strip is moved in the axial direction of the roll, it becomes difficult to obtain uniform reduction in the width direction of the metal strip, which may affect the surface properties such as the shape and roughness of the steel plate.
[0015] Furthermore, the method described in Patent Document 1 is limited to a 6-stage rolling mill having intermediate rolls and having a shift function for the intermediate rolls. Therefore, there is a problem that it cannot be applied to a 4-stage rolling mill that does not have intermediate rolls. Also, even with a 6-stage rolling mill, there is a problem that it cannot be applied to those that do not have a shift function for the intermediate rolls.
[0016] In the method described in Patent Document 2, high-roughness material is not always readily available in sufficient quantities. Therefore, if high-roughness material is in short supply, the number of times it can be applied is limited, which has the problem of affecting productivity.
[0017] The method described in Patent Document 3 requires a blasting device. Therefore, when applied to existing rolling mills that do not have a blasting device, there are problems such as high initial costs and increased maintenance burden.
[0018] This invention has been made in view of the above-mentioned problems, and aims to provide a method for temper rolling a metal strip that can suppress the formation of edge marks on the work roll while maintaining an appropriate surface roughness of the metal strip. [Means for solving the problem]
[0019] To solve the above problems, the present invention has the following features. [1] A method for temper rolling a metal strip using a temper rolling mill in which a plurality of rolling stands, each containing a pair of work rolls for rolling the metal strip, are arranged in one direction, A first installation step involves setting the work roll having a roughness of 1.50 to 1.90 μm on a rolling stand, A second installation step involves installing the work roll, which has a crown of 5 / 100 mm or less, on another rolling stand located downstream of the first rolling stand in the first direction, A pressure regulating load setting step, which sets the pressure regulating load of the aforementioned rolling stand to 0.60 to 0.95 × 10 kN / mm, A method for temper rolling a metal strip, including the following. [2] When the work roll of the first rolling stand is replaced, a first pressure-regulating load setting step is performed to set the pressure-regulating load of the first rolling stand to a first set load, The system includes a second pressure-regulating load setting step, in which, after the first pressure-regulating load setting step has been performed, the pressure-regulating load of one rolling stand is set to a second set load that is higher than the first set load, The method for temper rolling a metal strip according to [1], wherein in the first pressure adjustment load setting step, the first set load is set to 0.50 to 0.70 × 10 kN / mm. [3] The second installation step is performed on the rolling stand arranged at the most downstream among the rolling stands arranged in the one direction, and is the method for temper rolling of the metal strip according to [1] or [2]. [4] In the first installation step, the work roll having a higher roughness than the work rolls installed in the other rolling stands is installed in the one rolling stand, and is the method for temper rolling of the metal strip according to any one of [1] to [3]. [5] A temper rolling machine for a metal strip in which a plurality of rolling stands each including a pair of work rolls arranged to face each other are arranged in one direction, having rolling load setting means for setting the rolling pressure load of one of the rolling stands arranged in the one direction to be lower than that of the other rolling stands arranged downstream of the one rolling stand in the one direction, the roughness of the work roll of the one rolling stand is 1.50 to 1.90 μm, and the crown of the work roll of the other rolling stand is 5 / 100 mm or less, is a temper rolling machine for a metal strip. [6] A method for manufacturing a metal strip using a temper rolling machine in which a plurality of rolling stands each including a pair of work rolls for rolling the metal strip are arranged in one direction, a first installation step of installing the work roll having a roughness of 1.50 to 1.90 μm in one rolling stand, a second installation step of installing the work roll having a crown of 5 / 100 mm or less in the other rolling stands arranged downstream of the one rolling stand in the one direction, a rolling pressure load setting step of setting the rolling pressure load of one of the rolling stands arranged in the one direction to be lower than the rolling pressure load of the other rolling stands arranged downstream of the one rolling stand in the one direction and to be 0.60 to 0.95 × 10 kN / mm, after the first installation step, the second installation step, and the rolling pressure load setting step are executed, a rolling step of rolling the metal strip with the temper rolling machine, A method for manufacturing a metal strip, comprising the characteristics of a metal strip. [Effects of the Invention]
[0020] According to the temper rolling method for a metal strip of the present invention, by having a first setting step, a second setting step, and a pressure adjustment load setting step, it is possible to suppress the formation of edge marks on the work roll while maintaining an appropriate surface roughness of the metal strip. [Brief explanation of the drawing]
[0021] [Figure 1] This is a schematic diagram illustrating a temper rolling mill for metal strips. [Figure 2] This is an explanatory diagram showing the distribution of pressure-regulating load applied to a metal strip. [Figure 3] This graph shows the surface roughness in the width direction of the metal strip. [Figure 4] This is a flowchart showing a method for manufacturing a metal strip. [Figure 5] This graph shows the edge mark occurrence rate for the examples and comparative examples. [Modes for carrying out the invention]
[0022] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 shows a metal strip tempering mill 100. The metal strip tempering mill 100 is installed in equipment that performs continuous tempering.
[0023] As shown in Figure 1, the metal strip tempering mill 100 has a rolling section 10 for rolling the metal strip SS and a reduction device 20 for adjusting some of the rolling conditions of the rolling section 10. The metal strip SS is not particularly limited, but for example, steel sheets manufactured for cans can be used. Preferably, the metal strip SS has a width of 650 mm to 1100 mm. If the width is 650 mm or more, the occurrence of edge marks can be suppressed more effectively. If the width is 1100 mm or less, the difference in roughness in the width direction can be made smaller.
[0024] The rolling section 10 has a plurality of rolling stands 11a, 11b arranged in one direction D1. In this embodiment, the one direction D1 is the same as the rolling direction (hereinafter also referred to as the pressure adjustment direction) in which the metal strip SS is rolled and conveyed. The number of rolling stands is not particularly limited as long as there are multiple, but in this embodiment, two rolling stands are provided.
[0025] Each rolling stand 11a, 11b includes a pair of work rolls 12a, 12b arranged vertically opposite to each other. The pair of work rolls 12a, 12b are supported by a pair of backup rolls 13a, 13b. The pair of work rolls 12a, 12b are spaced apart in the vertical direction.
[0026] Therefore, the pair of work rolls 12a and 12b apply reduction by contacting the metal strip SS, which is the material to be rolled, as it passes between them. In addition, the backup rolls 13a and 13b support the pair of work rolls 12a and 12b from above and below, suppressing the deflection of the work rolls 12a and 12b. Note that the rolling stands 11a and 11b are not limited to the four-stage rolling mill shown in Figure 1, but may also be a six-stage rolling mill.
[0027] The roughness of the work rolls 12a and 12b of the rolling stand 11a, which is positioned on the front side of direction D1, should be 1.50 to 1.90 μm. The roughness of the work rolls 12a and 12b can be measured, for example, using a contact-type surface roughness measuring instrument as follows: A surface roughness meter is installed at a total of three locations in the work roll barrel section: the center and 200 mm from both edges. The average value of Ra obtained from three measurements at each width position is taken as the average Ra value for each width position. The roughness of the work roll is then obtained by further averaging the average Ra values for each width position obtained above. As a contact-type surface roughness measuring instrument, for example, a small surface roughness measuring instrument (SURFTEST SJ-210 series SJ-210 (standard drive, 0.75 mN type): manufactured by Mitutoyo Corporation) can be used.
[0028] The roughness of the work rolls 12a and 12b of the rolling stand 11a located on the front side should be higher than that of the work rolls 12a and 12b of the rolling stand 11b located on the rear side. For example, it is preferable that the roughness of the work rolls 12a and 12b of the rolling stand 11a located on the front side be 0.75 to 0.85 μm higher than that of the work rolls 12a and 12b of the rolling stand 11b located on the rear side.
[0029] The roughness of the work rolls 12a and 12b can be set using the same settings as those used to maintain the surface roughness of the metal strip when the metal strip is manufactured using an existing temper rolling mill 100. The following methods can be used to set the roughness of the work rolls 12a and 12b.
[0030] Furthermore, if three or more rolling stands are provided, it is preferable to set the work rolls of the frontmost rolling stand to the roughness described above.
[0031] The reduction device 20 adjusts the spacing between the work rolls 12a and 12b of each rolling stand 11a and 11b, i.e., the roll gap, so that the rolling load applied to the metal strip SS is a predetermined value. Therefore, the metal strip SS is subjected to the predetermined reduction adjusted by the reduction device 20 as it passes between the work rolls 12a and 12b of each rolling stand 11a and 11b. The reduction device 20 can also individually adjust the roll gap of the work rolls 12a and 12b of each rolling stand 11a and 11b.
[0032] The reduction device 20 sets the pressure regulating load of one rolling stand 11a located upstream in one direction D1 higher than that of other rolling stands 11b located downstream of the first rolling stand 11a in the same direction D1. In other words, the reduction device 20 functions as a rolling load setting means.
[0033] Figure 2 shows the distribution of the pressure-regulating load applied to the metal strip. Figure 2(a) shows an embodiment in which the metal strip is rolled using a work roll with a higher crown than the work roll shown in Figure 2(b). Figure 2(b) shows an embodiment in which the metal strip is rolled using a work roll with a lower crown than the work roll shown in Figure 2(a). In this embodiment, the crown refers to a so-called convex crown that protrudes outward from the axis of the work roll.
[0034] As shown in Figures 2(a) and (b), the pressure regulating load decreases in the width direction of the metal strip from the center towards the ends. This trend is more pronounced in the configuration shown in Figure 2(a), where the crown of the work roll is higher.
[0035] Figure 3 shows the surface roughness in the width direction of the metal strip. More specifically, Figure 3 shows the surface roughness in the width direction of the metal strip when the load of the rolling stand 11a located on the front side, the work roll crown, and the load of the rolling stand 11b located on the rear side are kept constant, while the work roll crown of the rolling stand 11b located on the rear side is changed. As shown in Figure 3, in the width direction of the metal strip, the surface roughness increases from the center towards the ends in the width direction, namely the cab side and the opposite side of the cab. This trend is more pronounced when the work roll crown of the rolling stand 11b located on the rear side is higher.
[0036] In the rolling stands 11a and 11b, the crown of the work roll of the rolling stand 11b located on the downstream side is set lower than the crown of the work roll of the rolling stand 11a located on the upstream side. The crown of the work roll of the rolling stand 11b located on the downstream side is set to 5 / 100 mm or less. By setting the crown of the work roll of the rolling stand 11b located on the downstream side in this way, the pressure regulating load applied to the edge of the metal strip SS can be increased, and the roughness in the pressure regulating direction can be made appropriate.
[0037] Furthermore, if three or more rolling stands are provided, the crown of the work roll of the last rolling stand should be 5 / 100 mm or less. The crown of the work roll can be measured by using a caliper gauge to determine the difference in diameter between the center and the outermost edge of the work roll.
[0038] The method for manufacturing a metal strip using the metal strip tempering mill 100 described above will now be explained. Figure 4 shows a flow chart for manufacturing a metal strip. As shown in Figure 4, The first installation step is performed by installing a work roll with a roughness of 1.50 to 1.90 μm into the rolling stand 11a on the front side (step S101).
[0039] Next, the second installation step is performed by placing the work rolls with a crown of 5 / 100 mm or less onto the rolling stand 11b located on the downstream side (step S102). Note that the first installation step in step S101 and the second installation step in step S102 may be performed in either order or simultaneously.
[0040] Furthermore, the pressure regulating load of the front-stage rolling stand 11a is set higher than the pressure regulating load of the rear-stage rolling stand 11b. More specifically, after the first installation step of step S101 and the second installation step of step S102 are performed, a first pressure regulating load setting step is performed in which the pressure regulating load of the front-stage rolling stand 11a is set to a first set load (step S103). The first set load is lower than the pressure regulating load of the other rolling stand, the rear-stage rolling stand 11b. The first set load is preferably set to 0.50 to 0.70 × 10 kN / mm.
[0041] After the first installation step of step S101, the second installation step of step S102, and the pressure adjustment load setting step of step S103 are performed, the rolling step is performed by rolling the metal strip in the temper rolling mill 100 (step S104).
[0042] When the rolling step of step S104 is executed, it is determined whether the first coil of the metal strip being rolled has been completed since the first pressure adjustment load setting step of step S103 was executed (step S105). That is, if the coil of the metal strip being rolled is the first coil (step S105: NO), the rolling step of step S104 continues while the first set load is maintained.
[0043] If the first coil is completed after the first pressure regulating load setting step has been performed (step S105: YES), the pressure regulating load of the rolling stand 11a located on the front side is set to a second set load that is higher than the first set load. The second set load is lower than the pressure regulating load of the other rolling stand, the rolling stand 11b on the rear side. Furthermore, it is more preferable that the second set load be set to 0.60 to 0.95 × 10 kN / mm.
[0044] After the second pressure adjustment load setting step of step S106 is performed, the rolling step is performed by rolling the metal strip in the temper rolling mill 100 (step S107).
[0045] As described above, the temper rolling method for a metal strip of the present invention comprises a first setting step, a second setting step, a first pressure adjustment load setting step, and a second pressure adjustment load setting step. This makes it possible to suppress the formation of edge marks on the work rolls 12a and 12b while maintaining an appropriate surface roughness of the metal strip.
[0046] In this embodiment, the second pressure regulating load setting step has been described in which the second pressure regulating load setting step is executed after the first pressure regulating load setting step has been performed and the first coil has finished. However, the second pressure regulating load setting step is not limited to this embodiment and may be executed at any arbitrary timing. [Examples]
[0047] (Test Example 1) Metal strips were manufactured using an existing temper rolling mill. The temper rolling mill used was a four-stage temper rolling mill consisting of two rolling stands. Of the two rolling stands, the one located upstream in the pressure adjustment direction is referred to as the front-stage rolling stand, and the one located downstream is referred to as the rear-stage rolling stand. Table 1 shows the pressure adjustment load and work roll conditions. In the descriptions in Table 1 and below, "target" refers to the target value measured in the actual measurement. The numerical range listed after "target" is the set value, physical property value, etc., set in the machine, etc., to obtain the "target" value.
[0048] [Table 1]
[0049] Below, the conditions prior to the change in settings for the existing metal strip temper rolling mill are described as the conventional conditions. Under the conventional conditions, the pressure regulating load of the front-stage rolling stand was set to 1.00 × 10 kN / mm. In this test, the pressure regulating load of the front-stage rolling stand was set to 0.80 × 10 kN / mm.
[0050] Setting the pressure regulating load too low may reduce the roughness of the metal strip. To suppress this reduction in metal strip roughness, the roughness of the work rolls on the front-stage rolling stand was set higher than under conventional conditions. The roughness of the work rolls on the front-stage rolling stand was determined as follows.
[0051] (Procedure 1) Under conventional conditions, the transfer rate was defined as the surface roughness of the mill exit side of the first coil of pressure adjustment relative to the roughness of the work rolls of the rolling stand on the upstream side. That is, the transfer rate (%) was calculated as: Transfer rate (%) = Steel sheet roughness of the first coil of pressure adjustment (μm) / Work roll roughness (μm). The transfer rate in the rolling direction and width direction of the metal strip was calculated. The roughness of the work rolls of the rolling stand on the upstream side under conventional conditions was 1.20 to 1.50 μm. (Step 2) If the pressure regulating load and roll conditions of the downstream rolling stand are not changed from the conventional conditions, it can be assumed that the surface roughness of the metal strip depends on the pressure regulating load and work roll roughness of the upstream rolling stand. Based on this assumption, the correlation coefficient between the pressure regulating load of the upstream rolling stand and the transfer rate was calculated. (Step 3) Based on the correlation coefficient calculated in (Step 2) and the pressure adjustment of the rolling stand on the preceding side, the roughness of the work roll was calculated to meet the surface roughness criteria described later.
[0052] As a result of the above procedure, the roughness of the work rolls of the rolling stand on the front side was set to target 1.70 μm (1.50~1.90).
[0053] (Evaluation of the roughness of metal strips) The surface roughness of metal strips manufactured under the conditions described in Table 1 was evaluated. The surface roughness of the metal strips was evaluated at three measurement positions in the width direction. The measurement positions for surface roughness were the edge on the cab side, the center, and the edge on the opposite side of the cab. The evaluation of surface roughness was performed using the surface roughness of metal strips manufactured under conventional conditions as a reference. References were established for surface roughness in the pressure adjustment direction and the width direction.
[0054] Furthermore, the difference in roughness between the center and edge of the metal strip was evaluated. Criteria were established for the roughness difference in both the pressure adjustment direction and the width direction. These criteria are shown in Table 2. These criteria were set based on the results of conventional conditions. Furthermore, the results of the evaluation based on the criteria in Table 2 are shown in Table 3. In Table 3, "○" indicates that the criteria are met, and "×" indicates that the criteria are not met. The pressure adjustment distance refers to the total pressure adjustment distance from the time the work roll was replaced with a new one until it was replaced again.
[0055] [Table 2]
[0056] [Table 3]
[0057] As shown in Table 3, the surface roughness in the width direction met the standard at all measurement locations. In contrast, the surface roughness in the pressure adjustment direction did not meet the standard because it exceeded the standard at the pressure adjustment distance of 0 km, i.e., in the first coil that was temper-rolled after the work rolls were rearranged.
[0058] Furthermore, regarding the difference in roughness, the difference in roughness in the width direction met the standard, but the difference in roughness in the pressure regulation direction was less than 100 km in pressure regulation distance, and the roughness of the edges was higher than that of the center, so it did not meet the standard.
[0059] The above tests revealed that simply adjusting the pressure regulating load and the work roll roughness was insufficient to achieve the same level of roughness and roughness difference in the metal strip as under conventional conditions. In particular, the surface roughness at the edges of the metal strip appears to be outside the standard range.
[0060] (Test Example 2: Setting the Work Role Crown) Based on the results of Test Example 1, the crown settings for the work rolls of the downstream rolling stand were adjusted. Table 4 shows the pressure regulating load and work roll conditions. Additionally, the load on the upstream rolling stand was targeted to 0.70 × 10 kN / mm only for the first coil, and to 0.80 × 10 kN / mm for the second coil and subsequent coils. The crown of the work rolls of the downstream rolling stand was set to 5 / 100 mm.
[0061] [Table 4]
[0062] Surface roughness and the difference in roughness between the center and edges were evaluated in the same manner as in Test Example 1. The results are shown in Table 5. The evaluation criteria were the same as in Test Example 1.
[0063] [Table 5]
[0064] In the comparative example of Test Example 1, the surface roughness of the first pressure-regulating coil after work roll rearrangement, and the difference in roughness in the pressure-regulating direction, did not meet the standards. In contrast, in the embodiment, these evaluations also met the standards, and it was found that products with surface roughness equivalent to that under conventional conditions could be manufactured. Furthermore, in the embodiment, not only surface roughness but also gloss and color tone were evaluated and confirmed to be equivalent to those under conventional conditions.
[0065] (Edge Mark evaluation) Furthermore, the edge mark suppression effect was compared with conventional conditions under the conditions of Test Example 2. Figure 5 shows the results of the edge mark suppression effect. As shown in Figure 5, the edge mark occurrence rate in the example was reduced by 73.1% compared to Comparative Example 2, in which the metal strip was manufactured under conventional conditions.
[0066] Thus, it was found that by adjusting the pressure regulating load and the roughness of the work rolls of the front-stage rolling stand, and adjusting the crown of the work rolls of the rear-stage rolling stand, it is possible to suppress the formation of edge marks while maintaining the surface roughness of the metal strip. [Explanation of symbols]
[0067] 100 Temper rolling mill for metal strips 11a Rolling stand 11b Rolling stand 12a Work Roll 12b Work Roll 13a Backup Roll 13b Backup Role
Claims
1. A method for temper rolling a metal strip using a temper rolling mill in which a plurality of rolling stands, each containing a pair of work rolls for rolling the metal strip, are arranged in one direction, A first installation step involves installing the work roll, whose roughness obtained by averaging the average Ra values of Ra measured using a contact-type surface roughness measuring instrument is 1.50 to 1.90 μm, into a single rolling stand. A second installation step involves installing the work roll, which has a crown of 5 / 100 mm or less, on another rolling stand located downstream of the first rolling stand in the first direction, A pressure regulating load setting step in which the pressure regulating load of the first rolling stand is set to 0.60 to 0.95 × 10 kN / mm and the pressure regulating load of the other rolling stand is set to 0.20 to 0.50 × 10 kN / mm, Includes, A method for temper rolling a metal strip, wherein the roughness of the work rolls of the other rolling stand, obtained by averaging the average Ra values of Ra measured using a contact-type surface roughness measuring instrument, is 0.75 to 0.85 μm.
2. When the work roll of the first rolling stand is replaced, a first pressure-regulating load setting step is performed to set the pressure-regulating load of the first rolling stand to a first set load, The system includes a second pressure-regulating load setting step, after the first pressure-regulating load setting step has been performed, in which the pressure-regulating load of one rolling stand is set to a second set load that is higher than the first set load. The method for temper rolling a metal strip according to claim 1, wherein in the first pressure adjustment load setting step, the first set load is set to 0.50 to 0.70 × 10 kN / mm.
3. The method for temper rolling a metal strip according to claim 1 or 2, wherein the second installation step is performed on the rolling stand that is located furthest downstream among the rolling stands arranged in the one direction.
4. A temper rolling mill for metal strips, in which a plurality of rolling stands, each containing a pair of work rolls for rolling a metal strip, are arranged in one direction, The rolling load setting means is configured to set the pressure regulating load of one of the rolling stands higher than that of other rolling stands located downstream of the first rolling stand in the first direction. The roughness of the work roll of the one rolling stand, obtained by averaging the average Ra values of Ra measured using a contact-type surface roughness measuring instrument, is 1.50 to 1.90 μm. A temper rolling mill for metal strips, wherein the crown of the work roll of the other rolling stand is 5 / 100 mm or less.
5. A method for manufacturing a metal strip using a temper rolling mill in which a plurality of rolling stands, each containing a pair of work rolls for rolling the metal strip, are arranged in one direction, A first installation step involves installing the work roll, whose roughness obtained by averaging the average Ra values of Ra measured using a contact-type surface roughness measuring instrument is 1.50 to 1.90 μm, into a single rolling stand. A second installation step involves installing the work roll, which has a crown of 5 / 100 mm or less, on another rolling stand located downstream of the first rolling stand in the first direction, A pressure regulating load setting step in which the pressure regulating load of the first rolling stand is set to 0.60 to 0.95 × 10 kN / mm and the pressure regulating load of the other rolling stand is set to 0.20 to 0.50 × 10 kN / mm, After the first installation step, the second installation step, and the pressure adjustment load setting step are performed, a rolling step is performed in which the metal strip is rolled in the temper rolling mill, Includes, A method for manufacturing a metal strip, wherein the roughness of the work rolls of the other rolling stand, obtained by averaging the average Ra values of Ra measured using a contact-type surface roughness measuring instrument, is 0.75 to 0.85 μm.