JP2010179316A - Method of manufacturing cold-rolled steel sheet and manufacturing equipment used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for stably manufacturing a cold-rolled steel sheet with good quality by preventing push-in flaw due to properties of specifically a product edge part and trimming after cold rolling, and also to provide an equipment used for the same. <P>SOLUTION: A pair of upper and lower circular rotary blades are pressed to a predetermined depth from the above and below with respect to the edge part of the steel sheet before pickling. Shearing is applied to the edge part in an unseparated state. Next the edge parts are separated by pinching with narrow width rolls arranged at the respective edge parts and capable of pinching only the edge parts, and then the pickling and the cold rolling are applied. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method and equipment for manufacturing a cold-rolled steel sheet, and in particular, a method for stably producing a cold-rolled steel sheet with good quality by preventing the properties and surface flaws of the product edge after cold rolling. And related to equipment.

  Cold-rolled steel sheets manufactured by pickling and cold-rolling hot-rolled steel sheets manufactured by hot rolling are used for a wide range of applications such as automobiles, electrical products, and building materials. The steel sheet after cold rolling becomes a final product through processes such as plating treatment, annealing heat treatment, leveler correction, and press working according to the application. In general, hot-rolled steel sheets often have defects at the edges, and cold rolling after pickling or pickling tends to cause operational troubles such as sheet breakage. In particular, in the case of a steel plate having a thin plate thickness, the edge properties are deteriorated during cold rolling, and the plate is easily broken. Therefore, trimming the edge of the steel plate before cold rolling has been carried out, but the edge properties after trimming often have burr, and the rolls are wrinkled in subsequent pickling or cold rolling, etc. Trouble was occurring. On the other hand, even in a steel sheet that has been cold-rolled after pickling the hot-rolled steel sheet after trimming, the edge portion tends to have a notch-like shape (also referred to as ear cracking, ear roughness, edge cracking, etc.), and after cold rolling It was easy to cause operational troubles such as plate breakage when passing through the plating line, annealing line, and leveler straightening. Further, it is needless to say that in applications where the edge portion is used as it is as the final product of the plate material, good edge properties without edge cracks 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 while preventing operational troubles.

  In patent document 1, in the process line which processes a strip steel plate, the apparatus which can remove the burr of the strip steel plate edge part which arises by trimming by rotating and pressing a cylindrical grindstone or a brush etc. is disclosed. is doing.

  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 called 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 the deterioration of the edge property in cold rolling, after the edge part of the hot-rolled steel strip before cold rolling is trimmed, the work hardening by trimming is carried out by machining with a grinder or a bite. A method for removing portions is disclosed.

JP-A-10-315108 JP-A-11-267713 JP-A-62-282811 JP 54-124857 A

"No slitting slitting" (The 63rd Symposium on Plasticity Processing, 1978, P36-45)

  As described above, it is extremely important in terms of the manufacturing process and product quality of the cold-rolled steel sheet that the edge portion has good properties in the steel sheet before and after the cold rolling.

  When the method disclosed in Patent Document 1 is applied, the end of the steel plate is burred by pressing a cylindrical grindstone or brush or the like on the edge of the steel plate with a rotatable structure over the entire length of the steel plate after trimming. To be removed. 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. A grindstone, a brush, or the like wears and deteriorates depending on the amount of use, so that the steel plate production efficiency decreases due to the replacement, and the maintenance cost also increases the production cost. Moreover, when it tries to apply with respect to a steel plate with thin plate | board thickness, there exists a problem of being easy to cause the plate breakage 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 the masher roll against the burr portion generated at the edge of the steel plate after trimming. This is the portion where the burr protrudes from the steel plate. Is simply pressed with a roll, so there is a problem that the degree of burr is lightened or only the action of changing the direction of protrusion to the horizontal direction is not achieved, and it does not improve the notched shape of the edge part. is there.

  When the conventional roll-cut 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 steel sheet before or after cold rolling. It becomes possible. However, the roll used for separating the edge portion that has been unseparated 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 is cut off, but when the same roll is used for steel plates with different plate widths, the edge of the narrow material is cut off. There is also a problem that the roll wrinkles generated in the above process are transferred to the surface of the wide material and cause quality defects. Also, if some of the burrs near the center of the sheet thickness are scattered and adhere to the steel sheet surface or roll surface of the edge separating roll, it bites between the upper and lower wide roll rolls and the steel sheet that are under great pressure. There is a problem that tends to become surface flaws.

  In connection with the trimming disclosed in Patent Document 3, a masher roll is a device that is usually applied to remove burr after trimming. It is a device with a small rolling force due to its structure, and when pressed against the steel plate edge, the local stress of the pressed part increases, and the burr localized at the plate edge can be pressed and removed. . 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, sufficient stress cannot be applied. 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 structure with higher strength is 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, pickling or cold rolling, so it cannot be performed online and requires a separate process. Become. In addition, when a part of the edge is removed by machining such as grinder or bite, the removed part is generated as chips and scattered on the steel sheet, causing surface flaws. Is also likely to occur.

  As a result of investigating conventional knowledge, along with the notched properties of the edge of the steel sheet, the steel sheet is cold-rolled while preventing surface flaws during trimming to stabilize a good quality cold-rolled steel sheet. I couldn't find any manufacturing technology.

  Therefore, the present invention provides a method and equipment for stably producing a cold-rolled steel sheet having good quality by preventing the properties of the product edge part after the cold rolling and the indentation due to the trimming. Objective.

  In order to achieve the above object, the present invention has the following features.

  [1] In a method for producing 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 rotary blades with respect to the edge portion of the steel sheet before pickling Is pressed to the specified depth from above and below, the edges are sheared to an unseparated state, and then the edges are separated by a narrow roll placed on each edge and capable of clamping only the edges. Then, pickling and cold rolling are performed, The manufacturing method of the cold-rolled steel plate characterized by the above-mentioned.

  [2] In 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 shapes with respect to the edge portion of the steel sheet before cold rolling A mechanism that shears the edge part to the unseparated state by pressing the rotary blade from the top and bottom to the predetermined depth, and then it is installed at each edge part, and only the edge part is clamped by a narrow roll that can clamp A trimming device comprising a mechanism for cutting off the edge portion, a pickling facility for pickling the steel plate that has passed through the trimming device and trimmed the edge portion, and a cold rolling mill for rolling the steel plate after pickling. A manufacturing facility for cold-rolled steel sheets.

  [3] The cold rolled steel sheet manufacturing facility according to [2], wherein the trimming device, the pickling facility, and the cold rolling mill are directly connected to each other.

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

The schematic diagram which shows the installation for manufacturing the cold-rolled steel plate in this invention. The schematic diagram which shows the installation for manufacturing the cold-rolled steel plate in a comparative example. The schematic diagram which shows the state in which the edge part became a notch-like property (it is also called an ear crack, ear roughness, an edge crack, etc.) in a cold-rolled steel plate. Schematic diagram showing a conventional trimming method. The enlarged view of the schematic diagram which shows the rotary blade of one side. The schematic diagram which shows the trimming process in the roll cut type trimming method. The figure which shows the pinching roll in the conventional roll cut type trimming method. The figure which shows the pinching roll in the roll cut type trimming method by this invention. The figure which shows the pinching roll in the roll cut type trimming method by this invention. The schematic diagram which shows the cut surface at the time of applying the conventional trimming method. The schematic diagram which shows the cut surface at the time of applying a roll cut type trimming method. The schematic diagram which shows the edge part vicinity at the time of performing the pickling after the trimming by the roll cut type trimming method. The figure which shows the edge crack depth in each trimming method. The figure which shows the steel plate surface defect generation number in each trimming method.

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

  FIG. 3 schematically shows a state in which the edge portion of the cold-rolled steel sheet has a notch-like property (also referred to as an ear crack, a rough ear, or an edge crack). When such edge properties occur in cold rolling, sheet breakage tends to occur and it becomes difficult to stably roll. Moreover, if it remains after cold rolling, it is a problem that wrinkles are likely to occur in the press of the next process. As a cause of the edge failure, defects at the edge of the hot-rolled steel sheet are listed first. Therefore, in order to remove the defect, trimming is usually performed before cold rolling. However, even if the hot-rolled steel sheet is trimmed, the actual situation is that notch-like properties occur at the edge of the cold-rolled steel sheet. Although this may occur depending on the material and cold rolling operating conditions, it has been found by examination of the present inventors that it is often caused by burr generated by trimming of the edge portion of the hot-rolled steel sheet. It was.

  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. 4, a pair of upper and lower circular rotary blades are pressed against the edge portion of the hot-rolled steel sheet from the upper and lower sides to a predetermined depth and cut. Here, 1 is a steel plate, 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. 5 shows an enlarged view of the rotary blade on one side. Reference numeral 1 denotes a steel plate, and 1A denotes a portion that is cut off by trimming. In FIG. 5, C is a horizontal gap (also referred to as a 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 wrap) of the upper and lower rotary blades, and the one where the overlap amount between both becomes larger is positive (+). In the conventional trimming method, the clearance C is set to a value substantially proportional to the thickness of the steel plate. FIG. 10 schematically shows a cross section of the edge portion after trimming by a conventional trimming method, wherein 31 is a sheared surface, 32 is a fractured surface, and 33 is a burr. Thus, it can be seen that burr that becomes the starting point of the edge crack occurs on the surface of the steel sheet. Moreover, it turns out that the corner | angular part 36 of the shear surface of a board surface is sharp. The schematic diagram of the cross section of the edge part in FIG. 10 shows the cross section on the right side of the steel plate in the arrangement of the upper and lower cutting blades shown in FIG.

  On the other hand, in the conventional roll cut trimming method, as shown in FIG. 6, the trimming wrap L is set to negative (−), the edge cut-off portion is set in an unseparated state, and then, as shown in FIG. This is a trimming method in which a steel plate is sandwiched between an upper roll 12 and a lower roll 13 to separate an unseparated portion of the edge. 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. Here, the roll for pinching applied by the prior art shown in FIG. 7 had a body length wider than the maximum plate width of the steel plate to be passed. Hereinafter, the pinching roll in the conventional roll cut type trimming method is also referred to as a wide roll. FIG. 11 schematically shows a cross section of an edge portion after trimming by a conventional roll cut trimming method, wherein 31 is a shear surface, 32 is a fractured surface, 34 is a sag, and 35 is a burr. Since the fracture surface exists only in the vicinity of the center of the plate thickness and not on the surface of the steel plate, the burr that becomes the starting point of the edge crack does not occur. Instead, a burr 35 is generated near the center of the fracture surface. In addition, while the plate surface on the shearing surface side that is formed when trimming with the upper and lower blades has a sharp corner portion 36, a sag 34 is generated on the shearing surface side that is formed when the roll is clamped, so the corner portion is You can see that it is rounded.

  Since the corner of the shearing surface located on the steel sheet surface generated by the above trimming is sharp, if the corner hits a threading roll or the like, wrinkles or missing corners may occur. It has been found that the surface properties of are adversely affected. This corner portion has a smooth shape as shown in 37 of FIG. 12 by pickling, so that wrinkles are not generated on the sheet passing roll. Therefore, it was found that trimming should be performed before pickling.

  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. 8 in the roll cut trimming method. If the roll body length is made as short as possible, the probability of biting scattered burrs and the like is reduced, and surface flaws can be suppressed, which is advantageous.

  When burrs or the like bite into the pinching roll, if there are rolls above and below, the rolling force between them is large, and the roll is easily bitten between the roll and the steel plate and easily becomes surface defects. On the other hand, if there is only a roll on either the top or bottom, there is no rolling force to sandwich the steel plate in the center of the plate width, so burrs caught between the roll and the steel plate are hard to be crushed and become surface flaws. It is difficult. In addition, even when the same roll is used for steel plates with different plate widths, because the wrinkles of the roll 13 generated by cutting off the edge portion of the narrow material do not have a rolling force to sandwich the steel plate at the central portion of the plate width with the wide material. It is difficult to become surface defects.

  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. As shown in FIG. 8, the upper roll need not be narrow and the lower roll need not be wide. For example, as shown in FIG. 9, the upper roll may be wide and only the lower roll may be narrow.

  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.

  Furthermore, when cold-rolling using a steel plate trimmed according to the present invention, edge cracks are remarkably reduced and sheet breakage is less likely to occur. Since burrs and the like are not easily scattered inside, the number of jumping flaws is reduced and cold rolling can be performed efficiently and with high quality.

  In FIG. 13, the edge crack depth in each trimming method to the edge part of a hot-rolled steel plate is shown. As the target material, a 1.2 mm thick hot rolled steel plate of SPCC steel was used. In the conventional trimming method, the edge portion was cut off with a clearance C of 0.10 mm and a lap L of +0.4 mm, and then the burr protruding from the steel sheet surface was pushed and bent laterally by a masher roll. In the roll-cut trimming method, the trimming was performed so that the edge portion was not separated with a clearance C of 0.05 mm and a lap L of −0.5 mm, and then the unseparated edge portion was separated by pressing with a roll from above and below. For cold rolling, a reverse four-stage rolling mill having a work roll diameter of 500 mm was used, and three passes were rolled at a reduction rate of about 20% per pass. The thickness of the steel sheet after the 3-pass rolling was about 0.6 mm, and the total cold rolling reduction was about 50%.

  In FIG. 14, the result of investigating the surface defect of the steel plate surface after cold rolling in each trimming method to the edge part of a hot-rolled steel plate is shown. Here, for the cold rolled steel sheet 10 coil having a width of 860 mm to 1200 mm obtained by cold rolling the 1.2 mm thick base plate of the SPCC steel to about 0.6 mm, an optical surface inspection device is provided on the steel sheet surface. Thus, defects having a size of 2 mm or more and a depth of 0.1 mm were detected and evaluated by the number per 100 m length.

  With respect to the edge crack depth in each trimming method shown in FIG. 13, the edge crack depth is large in the conventional trimming method, whereas the conventional wide roll cut trimming method, the narrow roll cut method before cold rolling. In the trimming method and the present invention, the edge crack depth was small, and the edge properties were good.

  In the conventional trimming method, sheet breakage occurred during cold rolling, but none occurred in the conventional wide roll cut trimming method and the present invention.

  In the number of wrinkles on the surface of the steel sheet shown in FIG. 14, there were many surface wrinkles in the conventional wide roll cut trimming method. This is presumed to be caused by the fact that there were many streak defects in the vicinity of the edge, and the roll wrinkles generated when the relatively narrow plate width was roll-cut were transferred to the surface of the wide steel plate. In addition, a part of the burr is scattered during trimming, and wrinkles caught between the wide roll and the steel plate are also affected.

  Even with the conventional trimming method, the number of ridges is large, and some edge cracks caused by burr are missing during cold rolling and jump between the work roll and the steel sheet, and the roll crease is transferred to the steel sheet surface. It is estimated to be.

  In the comparative example to which the narrow roll cut trimming method before cold rolling was applied, many streak defects were found near the edge portion of the upper surface of the steel sheet. As shown in FIG. 11, it is presumed that wrinkles occurred on the work roll due to the sharp corners of the edges generated during trimming, and the roll wrinkles were transferred to the steel sheet surface.

  On the other hand, in the method of the present invention, as shown in FIG. 12, since the steel plate edge portion was rounded by pickling, wrinkles were hardly generated on the work roll, and the surface quality of the steel plate surface was small with few wrinkles.

  As described above, the present inventors have intensively studied a manufacturing method and manufacturing equipment of a cold-rolled steel sheet having good properties and surface quality at the product edge after cold rolling, and have achieved the present invention.

  In the present invention, in a method of 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 pickling. 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. After the separation, a method of manufacturing a cold-rolled steel sheet characterized by pickling and cold rolling.

  In addition, in a facility that manufactures a cold-rolled steel sheet of 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 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 comprising a mechanism for separating parts, an equipment for pickling steel plates that have passed through these devices and trimmed edge portions, and a cold rolling mill for rolling the steel plates after pickling A cold-rolled steel sheet manufacturing facility was used.

  Furthermore, in order to produce a steel plate of good quality efficiently, the cold rolling steel plate manufacturing facility described above is arranged by directly connecting an edge trimming device, a pickling facility and a cold rolling mill. A continuous production facility for rolled steel sheets was used.

  The lower limit of the body length of the narrow roll used for roll cutting is sufficient if it is wide enough to stably roll the steel sheet. In this case, it is sufficient if it is 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, 200 mm or less is desirable in order to prevent burrs and the like from scattering and biting and generating surface flaws on the steel plate.

  Since either of the upper and lower rolls has a narrow width, the force acting when shearing the unseparated steel sheet is extremely large in the width direction where the rolls exist both in the upper and lower directions, and only one of the upper and lower rolls This is because the portion having no roll is extremely small, so that the roll wrinkle and the biting wrinkle hardly occur in the portion having only one of the upper and lower rolls.

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

  About the present invention, after trimming the edge part of a hot-rolled steel sheet and pickling in the pickling section, using the example of manufacturing a cold-rolled steel sheet in a cold tandem rolling mill composed of 5 stands, the details Explained.

  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 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 to remove iron oxide (scale) on the surface of the steel plate. Pickling section, 23 is a bridle roll for controlling the tension applied to the steel plate being threaded, 24 is a cold tandem rolling mill consisting of 5 stands of a four-high rolling mill, and 25 is after rolling It is a coil obtained by winding a cold rolled steel sheet. In FIG. 1, all of the cold rolling mills 24 are represented as a four-stage stand, but the present invention is not limited to a four-stage stand, and is a two-stage or six-stage roll stand. Alternatively, a configuration in which two-stage, four-stage and six-stage rolling stands are mixed may be used. Moreover, in FIG. 1, although the cold rolling mill 24 is described as 5 stands, it is not limited to the case of 5 stands, and may be 4 stands or 6 stands. In FIG. 1, the steel plate is passed in the direction of the arrow, and on the upstream side not shown in the figure, a payoff reel for delivering the hot-rolled steel plate coil, the tail end of the preceding material and the tip of the following material are connected. A welding device for matching, a looper portion for adjusting a plate passing speed during welding, and the like are arranged. The looper part may be arranged in the pickling section.

  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 welded to the preceding material, and then the edge portions on both sides are trimmed by 10 mm each. Here, in the trimming according to the present invention, in the trimming apparatus 20, the clearance C was set to 0.10 mm and the lap L was set to -0.5 mm. As the values of the clearance C and the lap L, appropriate values calculated in advance according to the plate 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, the roll of 21 is a narrow roll on at least one of the upper and lower sides as shown in FIG. 8 or FIG. In roll No. 21, in order to cut 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 this trimming method, the edge portion is not burred.

After removing the surface scale from the pickled section 22 on a hot rolled steel sheet having a thickness of 1000 mm by trimming both edges, the steel sheet is rolled to 0.5 mm by 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 steel plate as it is cold-rolled, 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 at less than 0.1 mm in all locations, and the edge properties were good. there were.

  In the manufacturing apparatus in which the trimming process, the subsequent pickling section, and the cold rolling process are directly connected as shown in FIG. Is significantly limited, and production efficiency is reduced. Further, since the chips generated by the machining are cold-rolled while being wound on the steel sheet, the risk of deterioration of the surface quality becomes extremely high, so that the application is impossible.

  In the example of the present invention, the best mode for carrying out the invention in the facility in which the trimming process, the pickling section, and the cold rolling mill are directly connected has been described, but the trimming process, the pickling section, and the cold rolling mill are respectively Even in the case of another facility, the same effect can be obtained by performing pickling after trimming and then performing cold rolling.

  As described above, according to the present invention, it is possible to provide a stable manufacturing method and manufacturing equipment for cold-rolled steel sheets that have good properties at the product edge after cold rolling and prevent wrinkles on the steel sheet surface. Become.

  The present invention will be described based on an example of manufacturing a cold rolled steel sheet in a cold tandem rolling mill having 5 stands. Implementation conditions are shown in Tables 1 and 2.

  As for the type of the cold rolling mill, 1-4 stands are 4 stages, 5 stands are 6 stages, and the work roll diameter of each stand is as shown in Table 2. Except for the cold tandem rolling mill, the other apparatuses are as shown in FIGS.

  The test material of an Example is a hot-rolled steel plate used as each base plate of SPCC steel which is a general cold-rolled steel plate, and SPFC340 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.

  In Examples 1 to 6 of the present invention, a roll-cut trimming method using a narrow roll as an upper roll as the trimming apparatus 20 and the pinching roll 21 shown in FIG. The trimming conditions are as shown in Table 1.

  In Comparative Examples 1 and 2, a roll-cut trimming method using a narrow roll as the upper roll as the trimming apparatus 20 and the pinching roll 21 shown in FIG. 2 was performed before cold rolling (after the pickling section 22). . The trimming conditions are as shown in Table 1.

  In the conventional examples 1-1 and 2, the conventional trimming method in which only the 20 trimming devices were used to completely separate the edge cut-off portion with the rotary blade was performed before pickling. The trimming conditions are as shown in Table 1. After trimming, the burr protruding from the steel sheet surface was pushed and bent laterally using a masher roll, and then passed through the pickling section 22.

  In Conventional Examples 2-1 and 2, the roll-cut type trimming method using a wide roll as the trimming apparatus 20 and the pinching roll 21 shown in FIG. The trimming conditions are as shown in Table 1.

As evaluation of the edge properties, the properties of the edge portions were examined by arbitrarily selecting 10 locations in the longitudinal direction of the steel sheets after cold rolling. In any part, the edge crack was good if it was less than 0.1 mm, and if there was a part of 0.1 mm or more even in one place, it was considered bad.
As an evaluation of the surface quality, an optical surface inspection device detects a defect with a size of 2 mm or more and a depth of 0.1 mm or more, and evaluates the number per 100 m length. If there was, it was considered good.

  As shown in Table 1, either the edge property or the surface quality was poor in the comparative example and the conventional example, whereas both the edge property and the surface quality were good in the inventive example.

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

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 Pinching roll for cutting off unseparated plate edge 22 Pickling section 23 Bridle roll 24 Cold tandem mill 25 Winding coil 31 Shear surface 32 Broken surface 33 34 Sagging 35 Burr 36 Corner on the surface side of the sheared surface after trimming 37 Corner on the surface side pickled after trimming

Claims (3)

  In the method of manufacturing a cold-rolled steel sheet having a predetermined size by cold rolling after pickling the hot-rolled steel sheet, a pair of upper and lower circular rotary blades from above and below the edge of the steel sheet before pickling. After pressing to a predetermined depth, the edge portions are sheared to an unseparated state, then installed on each edge portion, and after squeezing with a narrow roll capable of clamping only the edge portion, the edge portion is separated, A method for producing a cold-rolled steel sheet, characterized by pickling and cold rolling.   In a facility for producing cold-rolled steel sheets of a predetermined size by pickling the hot-rolled steel sheets and then cold rolling them, a pair of upper and lower circular rotary blades are placed on the edge of the steel sheets before cold rolling. A mechanism that shears the edge part to an unseparated state by pressing from above and below to a predetermined depth, and then installed on each edge part, and the edge part is clamped by a narrow roll that can clamp only the edge part. A trimming device comprising a cutting mechanism, a pickling facility for pickling a steel plate that has passed through the trimming device and has an edge trimmed, and a cold rolling mill for rolling the steel plate after pickling. Features cold-rolled steel sheet manufacturing equipment.   The cold-rolled steel sheet manufacturing equipment according to claim 2, wherein the trimming device, the pickling equipment, and the cold rolling mill are directly connected to each other.

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