JP2010089111A - Method and equipment for manufacturing cold-rolled steel sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and equipment for stably manufacturing cold-rolled steel sheets excellent in quality by preventing defective properties in the edge parts of a product after cold rolling and surface flaws caused by trimming. <P>SOLUTION: In the method for manufacturing the cold-rolled steel sheets having a predetermined size by cold-rolling the steel sheets 1 after hot rolling after pickling them, while a pair of upper and lower circular rotary cutting blades 10A, 11A, 10B, 11B are pressed against the edge parts of the steel sheets 1 before cold rolling to a predetermined depth from the upper and lower parts, shearing is applied to the edge parts until becoming in an unseparated state and, next, after cutting off the edge parts 1A, 1B by clamping edge parts with narrow width rolls 14A, 14B, 13 which are installed in the respective edge parts and with which only the edge parts are clamped and cold rolling is applied with a rolling mill having work rolls whose diameters are ≥300 mm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a manufacturing method and manufacturing equipment for cold-rolled steel sheets, and in particular, prevents poor quality and surface flaws at the product edge after cold rolling, and stably manufactures cold-rolled steel sheets with good quality. It relates to a method and equipment.

  A cold-rolled steel sheet is a steel sheet used for a wide range of applications such as automobiles, electrical products, and building materials. The steel sheet that has been cold-rolled becomes a final product through processes such as plating, annealing heat treatment, leveler correction, and press working according to the application. In general, steel sheets that have been cold-rolled tend to have a notch-like shape (also referred to as edge cracking, edge roughness, edge cracking, etc.), and plating lines, annealing lines, and leveler correction after cold rolling. It was easy to cause operational troubles such as plate breakage when passing through the plate or cold rolling itself. In particular, in the case of a steel plate having a thin plate thickness, the edge properties deteriorated during cold rolling, and the plate was easily broken. Needless to say, in applications where the edge portion is used as it is as the final product of the plate material, good edge properties without burr (also referred to as burr) are required. Therefore, trimming the edge portion of the steel sheet after cold rolling has been performed, but trimming over the entire length of the steel sheet increased in length by cold rolling, not only the work load is enormous, Yield decline was also invited. Further, when trimming a cold-rolled steel sheet, the edge property after trimming often has a burr, which has been a cause of wrinkles in press working. For this reason, various techniques have been developed for improving the properties of the product edge portion of a cold-rolled steel sheet.

  Patent Document 1 discloses an apparatus that can remove the burr at the end of the strip steel plate by rotating and pressing a cylindrical grindstone or brush in a process line for processing the strip steel plate.

  In Patent Document 2, after trimming the end of the strip-shaped metal plate, the masher roll is pressed against the burr portion of the end of the strip-shaped metal plate to remove the burr so that an appropriate rolling force distribution of the masher roll can be obtained. Discloses a method of inclining and pressing the masher roll.

  In Non-Patent Document 1, as a trimming method that does not generate burr, a trimming method is disclosed in which trimming is performed so that the edge portion is not separated by adjusting the trimmer blade, and then the unseparated edge portion is separated by pressing with a roll from above and below. is doing. This method is also referred to as a roll cut trimming method.

  Patent Document 3 discloses a roll-cut trimming method in which a steel plate is sandwiched from above and below by combining masher rolls.

On the other hand, in Patent Document 4, in order to prevent deterioration of the edge properties in the cold-rolled steel strip, after trimming the edge portion of the hot-rolled steel strip before cold rolling, machining by trimming is performed by machining with a grinder or a bite. A method for removing the cured portion is disclosed.
JP 10-315108 A JP-A-11-267713 JP-A-62-282811 JP 54-124857 A “No burr slitting” (plasticity and processing, Vol. 20, No. 219, 1979, P270-275)

  As described above, good quality of the edge portion of the cold-rolled steel sheet is extremely important in terms of manufacturing process and product quality.

  When the method disclosed in Patent Document 1 is applied, the end of the steel plate is pressed against the edge of the steel plate with a cylindrical grindstone or brush with a rotatable structure over the entire length of the cold-rolled steel plate. It removes the burr. Therefore, there is a problem that the work efficiency is remarkably deteriorated due to the addition of the process and the manufacturing cost is increased. Grinding stones, brushes, and the like are worn and deteriorated according to the amount of use, so that the steel plate production efficiency is reduced by the replacement, and the maintenance costs also increase the production costs. Moreover, when it tried to apply with respect to a steel plate with thin plate | board thickness, there existed a problem of being easy to cause the plate fracture | rupture resulting from the contact of a grindstone or a brush.

  When the method disclosed in Patent Document 2 is applied, the burr is removed by pressing a masher roll against the burr portion generated at the end of the cold-rolled steel plate. Since the part that protrudes from the bottom is simply pressed with a roll, there is a problem that the degree of burr is lightened or only the action of changing the direction of protrusion to the lateral direction can be achieved, and the edge property cannot be improved. there were.

  When the conventional roll cartridge type trimming method disclosed in Non-Patent Document 1 is applied, it is possible to eliminate the burr at the edge of the steel sheet by improving the trimming method itself in the cold-rolled steel sheet. However, the roll used for separating the edge portion that has not been separated by pressing with a roll from above and below is a roll having a body length wider than the maximum plate width of the steel plate as shown in FIG. When this wide roll is used up and down, the surface of the roll may be wrinkled when the edge part is cut off, but when it is used for cold-rolled steel sheets with different sheet widths using the same roll, the edge of the narrow material There is also a problem that the roll wrinkles generated by part separation are transferred to the surface of a wide cold-rolled steel sheet, and surface defects are easily caused. In addition, when part of the burr is scattered and adheres to the steel sheet surface or roll surface of the edge separation roll, it tends to bite between the upper and lower wide rolls and the steel sheet under large pressure, resulting in surface defects. There's a problem.

  In relation to the trimming disclosed in Patent Document 3, the masher roll is a device having a small rolling force due to its structure, but by pressing only on the steel plate edge portion, the local stress of the pressed portion increases. Thus, the burr localized at the edge of the plate can be pressed. However, when the smasher rolls as in Patent Document 3 are combined up and down to sandwich the steel sheet surface from above and below and try to separate the unseparated edge portion, a small rolling force is dispersed on the wide steel sheet surface, Therefore, a sufficient force cannot be applied to the edge portion. According to the study by the present inventors, it has been found that an unseparated portion cannot be separated and a reduction device having a sufficiently strong structure is separately required.

  When the method disclosed in Patent Document 4 is applied, after the edge portion of the hot-rolled steel strip before cold rolling is trimmed, a process of removing the work-hardened portion by trimming by grinding with a grinder or a bit is necessary. Therefore, there is a problem that the work efficiency is remarkably lowered. In general, the threading speed in such a machining process is significantly slower than the threading speed in trimming and cold rolling, so machining with these grinders and tools cannot be performed online. An offline process is required. In addition, when a part of the edge part is removed by machining such as a grinder or a bite, the removed part is generated as chips, so that it may be scattered on the steel plate and cause deterioration of the surface quality. Prone to occur.

  In addition, conventionally, there has been found a technique for stably producing a good quality cold-rolled steel sheet by simultaneously rolling the steel sheet while preventing surface flaws in trimming in combination with the properties of the steel sheet edge portion. There wasn't.

  Therefore, the present invention provides a method and equipment for stably producing a cold-rolled steel sheet with good quality by preventing the defective properties of the product edge part after cold rolling and surface flaws (indentation flaws) due to trimming. The purpose is to do.

  In order to solve the above problems, the present invention has the following features.

  [1] In a method for producing a cold-rolled steel sheet having a predetermined size by pickling a hot-rolled steel sheet and then cold rolling, a pair of upper and lower circular rotations with respect to the edge portion of the steel sheet before cold rolling The blade is pressed from above and below to a predetermined depth, and the edge portions are sheared to an unseparated state, and then installed on each edge portion, and the edge portion is clamped by a narrow roll capable of clamping only the edge portion. A method for producing a cold-rolled steel sheet, characterized by performing cold rolling with a rolling mill having a work roll having a diameter of 300 mm or more after separation.

  [2] In an equipment for manufacturing a cold-rolled steel sheet having a predetermined size by pickling the steel sheet after hot rolling and then cold rolling, a pair of upper and lower circular rotations with respect to the edge portion of the steel sheet before cold rolling A mechanism that presses the blade from the top and bottom to a predetermined depth and shears the edge part to an unseparated state, and then the edge is clamped by a narrow roll that is installed at each edge part and can clamp only the edge part. A trimming device composed of a mechanism for separating parts, and a cold rolling mill comprising a work roll having a diameter of 300 mm or more for rolling a steel plate that has passed through these devices and trimmed an edge portion. Production equipment for rolled steel sheets.

  According to the present invention, it is possible to stably produce a cold-rolled steel sheet having good quality by preventing property defects and surface flaws at the product edge after cold rolling.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 2 schematically shows a state in which the edge portion of the steel plate 1 has a notch-like shape (also referred to as an ear crack, a rough ear, or an edge crack) in the cold-rolled steel plate. When such edge properties occur in cold rolling, sheet breakage is likely to occur and it becomes difficult to perform stable rolling. Moreover, if it remains after cold rolling, it is a problem that wrinkles are likely to occur in the press of the next process. Note that the reason why the edge portion is notched may be affected by the material and cold rolling operating conditions, but this is due to burr generated by trimming of the edge portion with respect to the base plate before cold rolling. It has been found out by the present inventors that there are many cases.

  In order to stably produce a cold-rolled steel sheet that does not cause surface defects such as wrinkles on the surface of the steel sheet, the present inventors have achieved a good cold-rolled steel sheet. Focusing on the trimming method of the edge portion with respect to the base plate before cold rolling instead of after rolling, the present invention has been intensively studied.

  In the conventional trimming method, as shown in FIG. 3, a pair of upper and lower circular rotary blades are pressed from the upper and lower sides to a predetermined depth against the edge portion of the steel sheet before cold rolling and cut. Here, 1 is a steel plate, 1A and 1B are portions to be cut off by trimming (edge cut-off portions), 10A and 10B are upper rotary blades at both ends, and 11A and 11B are lower rotary blades, respectively. In order to explain the setting method of the rotary blade in detail, FIG. 4 shows an enlarged view of the rotary blades 10A and 11A on one side. In FIG. 4, C is a horizontal gap (also referred to as clearance) between the upper and lower rotary blades, and the direction in which the gap between the two opens is positive (+). L is the vertical overlap amount (also referred to as a lap) of the upper and lower rotary blades, and the one with the larger overlap amount is defined as positive (+). In the conventional trimming method, the clearance C is set to a value proportional to the plate thickness of the steel plate.

  In the conventional roll-cut trimming method, as shown in FIG. 5, the trimming wrap L is set to negative (−), the edge cut-off portions 1A and 1B are set in an unseparated state, and then as shown in FIG. In this trimming method, the steel plate 1 is clamped between the upper roll 12 and the lower roll 13 to separate the unseparated portions 1A and 1B of the edges. The edge cut-off portions 1A and 1B that have not been separated are separated from the main body of the steel plate 1 by the roll clamping pressure. Here, the rolls 12 and 13 for pinching shown in FIG. 6 had a body length wider than the maximum plate width of the steel plate 1 to be passed. Hereinafter, the pinching rolls 12 and 13 in the conventional roll cut trimming method are also referred to as wide rolls.

  In the roll cut trimming method, the present invention uses narrow rolls 14A and 14B installed at respective edge portions as rolls used for roll clamping pressure as shown in FIG. If the roll body length is made as short as possible, the probability of biting scattered burr is reduced, which is advantageous in that surface flaws can be suppressed.

  When burr or the like bites into the pinching roll, the rolling force between the rolls is large at the upper and lower portions, and the burr bited between the roll and the steel plate is crushed and easily becomes surface defects. On the other hand, in the part where only the upper and lower rolls are present, since there is no rolling-down force sandwiching the steel sheet, the burr that bites between the roll and the steel sheet is difficult to be crushed and is not likely to be a surface flaw.

  Therefore, it is not necessary to narrow the pinching roll in the unseparated portion both in the upper and lower directions, and only one of the rolls may be narrow, and the other roll may be wide.

  The body length of the narrow roll necessary for separating the unseparated edge cut-off portion may be approximately 10 times or more the plate thickness of the steel plate. Accordingly, the body length of the narrow roll may be 10 times or more the maximum specification plate thickness of the edge trimming apparatus. In addition, the position of the narrow roll is appropriately changed according to the plate width of the steel plate and the edge cut-off amount. In addition, what is necessary is just to implement on the conditions similar to the roll cut type trimming method using the conventional wide roll except applying a narrow roll to at least one of upper and lower sides and performing roll clamping.

  The lower limit of the body length of the narrow roll for roll cutting only needs to have a width that can stably roll cut the steel sheet. If it is the target, it may be 20 mm or more. In addition, since the upper limit is set on both sides, it is natural that the upper limit is half or less of the plate width. However, in order to prevent burr and the like from being scattered and generating surface flaws on the steel plate, it is preferably 200 mm or less.

  Further, the narrow roll of the present invention does not need to have a narrow upper roll and a lower roll as shown in FIG. 7, for example, as shown in FIG. 8, the upper roll 12 is wide, Only the lower rolls 15A and 15B may be narrow. Since either the upper or lower roll is narrow, the force acting when shearing the unseparated steel sheet is remarkably large in the part where the roll exists in the upper and lower sides in the width direction. This is because the portion where there is no roll is extremely small, and the roll wrinkle or bite flaw is less likely to occur in the portion where there is no roll on either the top or bottom.

  Further, the structure for supporting these rolls has sufficient support strength to shear the unseparated plate.

  Further, when cold rolling is performed using the trimmed steel sheet, edge cracks that occur during cold rolling from the burr are significantly reduced, and the sheet breakage is less likely to occur. Therefore, it is possible to roll to a thinner one by increasing the tension than before, and since burr and the like are less likely to be scattered during rolling, dimples are reduced, and efficient and high-quality cold rolling becomes possible.

  FIG. 9 shows the diameter of the work roll of the rolling mill (hereinafter referred to as the work roll) in the conventional trimming method, the conventional trimming + machining method, and the method of the present invention as each trimming method to the edge of the hot-rolled steel sheet before cold rolling. (Also referred to as diameter) and edge crack depth.

  The edge crack is a phenomenon in which even a slight residual burr (burr) is caused as a starting point in the trimming, and the edge portion is cracked and expanded by cold rolling.

  Here, the steel type is a 1.2 mm thick hot-rolled base plate made of SPCC steel, and the rolling mill is a reverse type four-stage rolling mill that can use any work roll diameter. Three-pass rolling was performed at 20%. The property of the edge part of the steel plate after 3 pass rolling was investigated, and the depth of the edge crack was evaluated. In addition, the plate | board thickness of the steel plate after 3 pass rolling was about 0.6 mm, and the cold total reduction was about 50%. In addition, work rolls having diameters of 100, 200, 300, 350, 400, 500, and 570 mm were used.

  FIG. 10 shows the relationship between the work roll diameter of the rolling mill and the size of the burr of the edge after one pass rolling in each trimming method of the edge of the hot-rolled steel sheet before cold rolling. The size of the burr (burr) was evaluated by the length of the burr (burr) extending downward by cutting the edge part in a cross section across the width direction.

  In the conventional trimming method, as shown in FIG. 3, a pair of upper and lower circular rotary blades are pressed from above and below to a predetermined depth against the edge portion of the steel sheet before cold rolling and cut. In the conventional trimming method, the clearance C is set to a value proportional to the plate thickness (in this example, 10% of the plate thickness), and the lap L is set to 0.5 mm.

  In the conventional trimming + machining method, after the edge portion is trimmed by the above-described conventional trimming method, burr or the like of the edge portion is further mechanically removed. In this example, after the conventional trimming is finished, a separate machining process is added, and the burr is removed by pressing the cylindrical grindstone against the edge of the steel plate while rotating.

  In the method of the present invention, a roll-cut trimming method is applied to trimming the edge portion of a hot-rolled steel sheet before cold rolling. In the roll cut method, as shown in FIG. 5, the trimming wrap L is set to a negative (−), the edge cut-off portion is set in an unseparated state, and then the steel plate is moved to the upper roll 12 as shown in FIG. And a trimming method in which an unseparated portion of the edge is cut by clamping with the lower roll 13. The edge cut-off portions 1A and 1B that have not been separated are separated from the steel plate main body by the roll clamping pressure.

  In the relationship between the work roll diameter and the edge crack depth in the conventional trimming method, the conventional trimming + machining method, and the method of the present invention shown in FIG. 9, when the work roll diameter exceeds 300 mm in the conventional trimming method, the edge sharply appears. It can be seen that the crack depth increases. In the conventional trimming + machining method, the size of the edge crack does not increase even if the cold rolling reduction increases. In the method of the present invention, the size of the edge crack increases even if the cold rolling reduction increases. I never did. That is, when the work roll diameter exceeds 300 mm by the conventional trimming method, the edge property after cold rolling deteriorates, whereas in the present invention, the edge property after cold rolling does not deteriorate.

  The relationship between the work roll diameter and the burr size in the conventional trimming method, the conventional trimming + machining method, and the method of the present invention shown in FIG. , The burr is small, but it can be seen that the burr increases as the work roll diameter increases. When the work roll diameter exceeds 300 mm, the burr is rapidly increased. It is estimated that the work roll diameter in cold rolling affects the burr at the edge due to the contact length (also called contact arc length) between the work roll and the steel plate during cold rolling. . That is, when the work roll diameter is small, the contact length between the work roll and the steel plate is shortened, so that the contact pressure between the roll and the steel plate also increases, and the burr portion is crushed and disappears by rolling. As the work roll diameter increases, the contact length between the work roll and the steel plate also increases, so a region where the contact pressure between the roll and the steel plate is small is generated, and it is estimated that it remains only by being bent outward at that portion. Is done. For this reason, as shown in FIG. 9, when the work roll diameter exceeds 300 mm, it is estimated that the edge cracks become large. In the conventional trimming + machining method and the method of the present invention, almost no burr was observed.

  Here, when the work roll is smaller than 300 mm, the flatness of the steel sheet is likely to be poor due to the axial deflection of the roll, so the width of the rollable steel sheet is restricted or the axial deflection is controlled. For this reason, a rolling facility having a special structure is required, so that productivity is significantly reduced.

  Therefore, in the present invention, a rolling mill using a work roll having a diameter larger than 300 mm is adopted, and in order to improve the edge properties of the cold-rolled steel plate in this rolling, additional steps such as machining are increased. In order to efficiently produce a cold-rolled steel sheet, the present inventors have intensively studied a trimming method for a hot-rolled steel sheet before cold rolling to arrive at the present invention.

  In the present invention, in the method of manufacturing a cold-rolled steel sheet in which a steel sheet after hot rolling is pickled and then cold-rolled to produce a cold-rolled steel sheet having a predetermined size, the edge portion of the steel sheet before cold rolling is used. Then, press the pair of upper and lower circular rotary blades from above and below to a predetermined depth, apply shear to the edge part to an unseparated state, and then squeeze the edge part by pressing with the upper and lower rolls. It was decided to perform cold rolling with a rolling mill having a work roll.

  Also, in cold-rolled steel sheet manufacturing equipment for producing cold-rolled steel sheets of a predetermined size by pickling the hot-rolled steel sheets and then cold-rolling them, the edge portions of the steel sheets before cold rolling And a mechanism for pressing the pair of upper and lower circular rotary blades from above and below to a predetermined depth and shearing the edge part to an unseparated state, and then a mechanism for pressing the upper and lower rolls to separate the edge part. A cold-rolled steel sheet manufacturing facility comprising a trimming device and a rolling mill having a work roll having a diameter of 300 mm or more is provided.

  Regarding the upper limit of the diameter of the work roll, there is no upper limit in terms of edge properties, but the work roll diameter in industrial cold rolling is about 600 mm. The upper limit is also about 600 mm.

  The present invention will be described in detail using an example in which a cold-rolled steel sheet is manufactured by a cold tandem rolling mill composed of 5 stands.

  FIG. 1 is a diagram schematically showing a part of a process for producing a cold-rolled steel sheet using a cold tandem rolling mill according to the present invention. In FIG. 1, 1 is a cold-rolled steel plate, 20 is a trimming device, 21 is a roll for clamping the steel plate from above and below to separate the unseparated portion of the edge from above and below, and 22 is applied to the steel plate in the plate. A bridle roll for controlling the tension, 23 is a cold tandem rolling mill in which four-stage rolling rolls are composed of 5 stands, and 24 is a coil around which the rolled cold-rolled steel sheet is wound. In FIG. 1, the steel plate is passed in the direction of the arrow, and on the upstream side not shown in the figure, the payoff reel for delivering the hot rolled coil, the tail end of the preceding material and the tip of the following material are joined together. There are disposed a welding apparatus for the purpose, a looper part for adjusting a plate passing speed during welding, a pickling section for removing iron oxide (scale) on the surface of the hot-rolled steel sheet, and the like. In addition, the work roll diameter of the cold tandem rolling mill in the example of the present invention is 500 mm for all five stands.

  The trimming device 20 has circular rotary blades arranged on both edges of the steel plate, and can adjust the blade clearance C and lap L as shown in FIG.

  In the present invention example, an example in which a cold-rolled steel sheet having a thickness of 0.5 mm and a width of 1000 mm is manufactured from a hot-rolled steel sheet having a thickness of 2.0 mm and a width of 1020 mm will be described. The steel type is SPCC steel.

  The hot-rolled steel sheet paid out from the payoff reel is trimmed by 10 mm on both edge portions after the surface scale is removed in the pickling section. Here, in the trimming according to the present invention, the clearance C was set to 0.1 mm and the lap L was set to −0.5 mm in 20 trimming apparatuses. As the values of the clearance C and the lap L, appropriate values calculated in advance according to the thickness were set. Under this condition, the edge cut-off portion is in an unseparated state. Then, the steel plate is clamped from above and below with 21 rolls, and the unseparated portion of the edge is separated from above and below. Here, since the roll of 21 only cuts off the uncut-off edge cut-off portion, the roll gap may be set to the same value as the thickness of the steel plate. According to the trimming method of the present invention, the edge portion is not burred.

A 2 mm thick pickled hot rolled steel sheet having a width of 1000 mm with both edges trimmed is reduced to 0.5 mm with a 5-stand cold tandem rolling mill. The reduction rate of each stand was set to be uniform, and the tension applied to the steel plate between the stands was set to 10 kgf / mm ² . This is a common cold rolling operation mode.

  About the cold-rolled steel sheet after cold rolling, 10 points were selected arbitrarily in the longitudinal direction, and the properties of the edge portions were investigated, but the edge cracks were extremely small, less than 0.1 mm, and the edge properties were good in all locations. Met.

  In addition, in the manufacturing apparatus in which the trimming process and the subsequent cold rolling process as shown in FIG. 1 are directly connected, the machine speed such as a grinder or a bite is very limited, so the production speed is significantly limited. Efficiency is reduced. Further, since the chips generated by machining are cold-rolled while being wound on the steel sheet, the risk of deterioration of the surface quality becomes extremely high, so that application is impossible.

  As described above, according to the present invention, it is possible to provide a method for manufacturing a cold-rolled steel sheet having good properties at the product edge after cold rolling.

  As Example 1 of the present invention, an example in which the present invention is applied to the production of a cold-rolled steel sheet in a cold tandem rolling mill having five stands shown in FIG. 1 will be described.

  The specimens are SPCC steel, which is a general cold-rolled steel plate, and hot-rolled steel plate, which is a base plate for SPFC 340, which is a high-tensile steel plate. The base plate thickness is 1.6 to 2.6 mm, and the thickness after cold rolling is 0.6 to 1.4 mm.

  Implementation conditions are shown in Table 1.

  In the inventive examples 1 to 6, trimming was performed using the trimming device 20 and the pinching roll 21 shown in FIG. The trimming conditions are as shown in Table 1.

  In Comparative Examples 1 and 2, the conventional trimming method in which only the trimming device 20 was used to completely separate the edge cut-off portion with the rotary blade was performed. The trimming conditions are as shown in Table 1.

  In Comparative Example 3, rolling was carried out experimentally using a work roll having a work roll diameter of 250 mm using the same equipment as the invention example. However, due to poor flatness during rolling, the steel sheet broke, making rolling impossible.

  As an evaluation of edge properties, about cold-rolled steel sheets after cold rolling, the properties of the edge portions were investigated by arbitrarily selecting 10 locations in the longitudinal direction, and if the edge cracks were less than 0.1 mm at any location, they were good If there was a portion of 0.1 mm or more even at one location, it was judged as defective.

  As shown in Table 1, the edge properties were poor in the comparative examples, whereas the edge properties were good in all of the inventive examples.

  From the above results, according to the present invention, it is possible to produce a cold-rolled steel sheet having good properties at the product edge after cold rolling.

The figure which showed typically the equipment for manufacturing the cold-rolled steel plate in this invention The figure which shows typically the state in which the edge part became the shape of a notch shape (it is also called an ear crack, a rough ear, an edge crack, etc.) in a cold-rolled steel sheet. Schematic diagram of conventional trimming method Schematic diagram enlarging the rotary blade on one side Schematic diagram showing roll-cut trimming method The figure which shows the conventional wide pinching roll The figure which shows the pinching roll in the roll cut trimming method by the example of this invention The figure which shows the pinching roll in the roll cut trimming method by the example of this invention Diagram showing the relationship between work roll diameter and edge crack depth Diagram showing the relationship between the work roll and the edge burr size

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel plate 1A, 1B The part to cut off by trimming 10A, 10B Upper rotary blade 11A, 11B Lower rotary blade 12 Upper wide pinching roll 13 Lower wide pinching roll 14A, 14B Upper narrow pinching roll 15A , 15B Lower narrow pinching roll 20 Trimming device 21 Pinning roll for cutting off unseparated plate edge 22 Bridle roll 23 Cold tandem rolling mill 24 Winding coil

Claims (2)

  In a method of manufacturing a cold-rolled steel sheet of a predetermined size by pickling the steel sheet after hot rolling and then cold-rolling, the upper and lower circular rotary blades are moved up and down with respect to the edge portion of the steel sheet before cold rolling. After pressing to a predetermined depth and shearing the edge part to an unseparated state, the edge part is then separated by being clamped by a narrow roll that is installed on each edge part and can clamp only the edge part. A method for producing a cold-rolled steel sheet, wherein cold rolling is performed by a rolling mill having a work roll having a diameter of 300 mm or more.   In a facility that manufactures a cold-rolled steel sheet of a predetermined size by pickling the hot-rolled steel sheet and then cold-rolling it, the upper and lower circular rotary blades are moved up and down against the edge of the steel sheet before cold rolling. To the predetermined depth and shearing the edge part to the unseparated state, and then installed on each edge part, and the edge part is separated by clamping with a narrow roll that can clamp only the edge part A trimming device comprising a mechanism, and a cold-rolled steel plate comprising a cold rolling mill having a work roll having a diameter of 300 mm or more for rolling a steel plate that has passed through these devices and trimmed an edge portion. production equipment.

Images