JP2010264493A - Device and method for winding high-strength thick hot-rolled steel sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for winding a high-strength thick hot-rolled steel sheet around a coil in such a state that the springback deformation of the high-strength thick hot-rolled steel plate is reduced. <P>SOLUTION: A winding device having pinch rolls, wrapper rolls and a mandrel is provided with a bending/unbending means composed of three rolls, wherein the high-strength thick hot-rolled steel plate which is passed through the pinch rolls and guided to the mandrel is subjected to bending and unbending work in winding the steel sheet, thereby the springback of the coil is suppressed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a winding device and a winding method for winding a high-strength, thick hot-rolled steel sheet around a coil.

  In recent years, the demand for large-diameter thick-walled high-strength pipe materials such as X70 to 100 in the API standard has been increased mainly for the purpose of improving the transportation efficiency of resources such as crude oil and natural gas in the continental pipeline. In order to efficiently transport these resources, high internal pressure is applied to the inside of the pipe, and characteristics such as high toughness and high strength are also considered for pipe materials in consideration of crustal deformation due to use in cold regions and earthquakes. It has become very important. The pipes used in these pipelines have a large diameter of about 15 to 25 mm and an outer diameter of about 20 inches or more, and after forming the short side of a thick steel plate, which is a vertically long shape, into a circle in the past UOE pipes are often used in which the butt portion is piped by submerged arc welding in the longitudinal direction. Usually, a thick steel plate is manufactured in a substantially rectangular shape by multi-pass rolling in a thick plate mill having one or two hot slabs, and the product length is about 30 m at the maximum. is there.

  On the other hand, in recent years, a thick steel plate is rolled by a hot rolling (hot strip mill) line for thin plate rolling and wound into a coil shape to form a coil of a hot rolled steel plate (hot rolled coil), and then the coil is wound. In addition to the electric resistance welded tube that is unrolled, there is an increasing demand for a spiral steel tube that is formed into a pipe while welding a butt portion at the end of the plate width while simultaneously forming a hot-rolled steel plate into a spiral shape in the longitudinal direction. The hot-rolled coil can be manufactured to a maximum of about 45 tons. For example, if the thickness is 20 mm and the plate width is about 1900 mm, the length of the hot-rolled steel plate is about 151 m, and when it is formed into a spiral steel pipe having a diameter of 28 inches The pipe length is about 128m. Thus, by using a hot-rolled steel sheet coil as the base material before forming the pipe, it is possible to manufacture a long pipe continuously as compared with the case of manufacturing from a thick steel sheet, and thus an improvement in productivity can be expected.

  By the way, the hot-rolled steel sheet (sometimes referred to as a hot strip or simply a strip) after passing through the finishing mill of the hot strip mill in the hot-rolled steel sheet production line is usually wound around a coil by a coiler device as shown in FIG. Taken. That is, the front end portion 1a of the hot-rolled steel sheet 1 is guided downward between the apron 2 and the throat guide 4 by the pinch rolls 3a and 3b, and a plurality of wrapper rolls arranged around the mandrel 7 5 (5a to 5d), the arc-shaped strip guide 6 and the mandrel 7 are sequentially bent by a three-point support state and wound around a rotating mandrel. Next, the winding proceeds, and finally the hot rolled steel sheet is wound into a coil shape to form a hot rolled coil. When the winding is completed, the mandrel is reduced in diameter so that the coil can be pulled out.

  Then, normally, at the end of the winding of the hot rolled coil, the mandrel is stopped so that the tail end portion 1b of the hot rolled steel sheet is positioned below the coil as shown in FIG. Next, during winding, the coil car (not shown in FIG. 3) waiting under the coil is lifted, and the cradle roll 8 provided in the coil car is brought into contact with the coil tail end 1b. The mandrel 7 is reduced in diameter and the wrapper rolls 5a to 5d are opened after the loose weight of the tail end 1b is suppressed by its own weight, and the cradle roll 8 of the coil car (not shown) is mounted as it is. The coil car is then lowered and the coil is extracted from the coiler device (winding device). And the hot rolled coil extracted from the coiler device is conveyed to a banding device installed adjacent to the coiler to prevent winding looseness during conveyance, and one or a plurality of thin steels The band of the belt is annularly attached to the outermost peripheral portion thereof and bound.

  However, in a high-strength thick-walled hot-rolled steel sheet, since the cross-sectional area of the steel sheet is large and the strength is very high, it is very difficult to apply tension for winding tightly during winding. In general, a high strength material has a very large spring back after bending, and after coil winding is completed, the cradle roll 8 waiting under the coil is raised and pressed against the coil, and then the coil is extracted. Therefore, when the wrapper rolls 5a to 5d are retracted and the diameter of the mandrel that has been the center of coil rotation is reduced, the elastic strain component fixed by the mandrel 7 of the coil and the wrapper rolls 5a to 5d is released, and the coil is spring-loaded. Backing occurs and loosening occurs, and winding looseness on the outer periphery of the coil is particularly significant.

  FIG. 6 shows an example of the winding shape when the coil is pulled out after winding the high-strength thick material. However, the coil back is loosened due to the occurrence of the spring back. If the coil is loose enough, the coil cannot be lifted up and pulled out from the coiler (winding device), the coil vibration during transport in the coil car becomes significant, and the coil becomes unstable. After hanging, there was a problem that the band was cut during transportation. Even if the coil cools down to room temperature without any problem, the phenomenon that the tail end part of the next process, for example, at the moment of cutting the tie band in the pipe forming line, is generated by the springback. ) There was a problem such as damage to the equipment, and it was necessary to establish some countermeasure technology.

  Thus, although there are many problems in winding up the high-strength thick steel plate, for example, in Patent Document 1, it is difficult to bend the leading edge of the thick steel plate with a pinch roll or a wrapper roll. In order to improve this, the outer diameter of the mandrel is expanded by about 3 turns of the inner winding, the adhesion between the mandrel and the steel plate is improved to prevent slipping, and the coil is wound up. A method for suppressing the deterioration of the shape has been proposed.

  When winding a high-strength thick-walled hot-rolled steel sheet into a coil shape by the above-described conventional winding method, the tip can be handled by, for example, the technique disclosed in Patent Literature 1, Winding loosening is likely to occur due to springback at the portion other than the tip, especially at the tail end of the strip on the outer periphery side of the coil, and in the vicinity thereof, and there are many problems in handling coil winding and unloading as described above. It was.

  For this reason, even in a hot-rolled steel sheet production line equipped with a strong rolling mill capable of rolling high-strength thick-walled steel sheets, whether or not the coil can be wound, pulled out or conveyed by a winding device is high-strength and thick-walled hot-rolled. It is no exaggeration to say that it is decided whether or not to manufacture steel sheets.

JP 2003-80313 A

  The present invention has been made in view of the above circumstances, and is capable of winding a high-strength thick-walled hot-rolled steel sheet that can be wound on a coil with reduced springback. It is an object of the present invention to provide an apparatus and a winding method.

The present invention employs the following means in order to solve the above problems.
[1] A winding device for winding a high-strength, thick-walled hot-rolled steel sheet around a coil having a pinch roll, a bending / returning means comprising three rolls, a wrapper roll and a mandrel, and bending / returning Each roll of means has a central axis of rotation in a direction parallel to the sheet width direction of the high-strength hot-rolled steel sheet, and the means is bent into the hot-rolled steel sheet that passes through the pinch roll and is guided to the mandrel. A winding device for winding a high-strength thick-walled hot-rolled steel sheet around a coil, characterized by being able to bend back.
[2] A winding method for winding a high-strength thick-walled hot-rolled steel sheet around a coil by a winding device having a pinch roll, a bending / unbending means comprising three rolls, a wrapper roll, and a mandrel. The hot-rolled steel sheet guided by a mandrel after passing through a roll is subjected to bending / unbending processing by bending / rewinding means to reduce winding looseness due to the spring back of the coil, and to take up Winding method of winding a high-strength, thick hot-rolled steel sheet around a coil.
[3] After winding the tip of the high-strength thick steel plate around the mandrel, it is bent and unbent by means of bending and unbending to reduce winding looseness due to the coil springback and take up. A winding method for winding the high-strength thick hot-rolled steel sheet according to [2] around a coil.
[4] Either [2] or [3], wherein the bending / rewinding condition of the bending / rewinding means is set according to the steel type, coiling temperature, coil weight, plate thickness, and plate width. A winding method for winding a high-strength thick hot-rolled steel sheet according to claim 1 around a coil.
As the high-strength thick steel plate, in the present invention, the definition of high strength is X65 or more in the API standard, and the thick hot-rolled steel plate is a product thickness of 15 mm or more.

  According to the present invention, a winding device having a pinch roll, a wrapper roll, and a mandrel is provided with bending / bending means comprising three rolls, and the high strength is guided through the pinch roll to the mandrel. By applying a bending / unbending process to a thick steel plate, the steel plate can be wound with reduced springback.

The figure which shows the winding apparatus of the high intensity | strength thick hot-rolled steel plate by this invention Schematic diagram showing the action of bending and unbending in the present invention The figure which shows the winding state of the coil by this invention The figure which shows typically the coil winding state without winding looseness (lifting) Diagram showing a typical winding device A diagram schematically showing the coil winding state with loose winding (lifting)

  As a result of intensive studies on the technology for suppressing coil loosening due to springback of this high-strength thick-walled hot-rolled steel sheet coil, the present inventors have been wound around a mandrel of a coiler device (winding device). Immediately before, the present inventors completed the present invention by discovering that coil winding loosening due to springback can be prevented by applying appropriate bending and bending back processing with a three-point bending roll capable of bending and bending back to a hot-rolled steel sheet. .

Here, the winding method by the coiler apparatus (winding apparatus) of a general hot-rolled steel sheet is explained in full detail based on FIG. This winding method is basically followed in the present invention except that the bending / bending process described above is added.
As already mentioned, the tip 1a of the hot-rolled steel sheet 1 is guided downward between the apron 2 and the throat guide 4 by the pinch rolls 3a and 3b, and is further disposed around the mandrel 7. The plurality of wrapper rolls 5 (5a to 5d), the arc-shaped strip guide 6 and the mandrel 7 are sequentially bent and wound around the rotating mandrel.
Generally, when winding the front-end | tip part 1a of the hot rolled sheet steel 1 with a coiler apparatus, the peripheral speed of each roll, such as the pinch roll 3, the mandrel 7, and the wrapper rolls 5a-5d, is the thickness and hardness of the hot rolled sheet steel 1. In accordance with (strength) and the like, the value is adjusted to a value having a lead rate of 10 to 30%, that is, a speed that is 10 to 30% faster than the conveying speed of the hot-rolled steel sheet 1. At this time, the lead rate of the mandrel 7 and the wrapper rolls 5 a to 5 d is set to be equal to or higher than the lead rate of the pinch roll 3.

  The lead rate is cleared at the time when the winding of the tip of the hot-rolled steel sheet 1 is completed. Thereafter, the conveyance speed of the hot-rolled steel sheet 1 is substantially equal to the conveyance speed (except for the effects of heat shrinkage due to cooling and width shrinkage due to tension). Meaning) is controlled to the peripheral speed synchronized with. In FIG. 5, the number of wrapper rolls is four, but there are also three, and there are generally three to four coiler devices for hot-rolled steel sheets.

  In the coiler device, if the leading end of the hot rolled steel sheet 1 is loosened and is wound in a wavy manner, the subsequent winding cannot be continued or even if it is fortunately wound, When the winding wound up and overlaps outside, the winding becomes thicker and the size that protrudes from the housing of the coiler.As a result, it becomes clogged and cannot be pulled out. Damage to each part of the coiler device is great, and it takes many hours to recover.

In any case, in order to prevent such a situation from occurring, when winding the tip of the hot-rolled steel sheet 1 with a coiler device, in order to minimize the looseness of the hot-rolled steel sheet 1, the hot-rolled steel sheet 1 until the leading edge 1a starts to wind around the mandrel 7 until the winding is completed, the peripheral speed of each roll such as the pinch roll 3, the mandrel 7, and the wrapper rolls 5a to 5d is given a read rate, By winding the steel sheet 1 while pulling, the tip of the hot-rolled steel sheet 1 is loosened and prevented from being wound and wound.
In addition, although the completion time of winding changes with the intensity | strength etc. of a hot-rolled steel plate, it is normally set to the time when a front-end | tip part is wound about 3-5 turns.

  And after completion of winding of the front-end | tip part of the hot-rolled steel plate 1, the mandrel 7 is substantially equal to the conveyance speed of the hot-rolled steel plate 1, that is, the conveyance speed of the hot-rolled steel plate 1 on the exit side of the final rolling mill of the finish rolling mill. The winding up to the tail end is performed while controlling the tension close to the desired tension with the pinch roll 3 while synchronizing with the pinch roll 3.

Furthermore, after the winding has progressed and the tail end portion 1b of the hot rolled steel sheet 1 has passed through the pinch roll 3, tension does not act on the hot rolled steel sheet 1. At least one of the wrapper rolls 5a to 5d that has been retracted is pressed against the outer periphery of the coil to suppress loosening of the coil tail end 1b.
In addition, when the tail end part of a hot-rolled steel plate comes to about 20 m before a coiler, the conveyance speed (wind-up speed) of a hot-rolled steel plate is decelerated toward the completion | finish of winding.

  Then, normally, at the end of coil winding, the mandrel is stopped so that the tail end portion of the hot-rolled steel sheet is positioned below the coil. Thereafter, as shown in FIG. 4, a coil car (not shown) including two cradle rolls 8 is lifted, brought into contact with the cradle roll 8 at the coil tail end, and due to a bending moment generated by the weight of the coil 1. After the spring back is suppressed, the mandrel 7 is reduced in diameter and mounted on the cradle roll 8 of the coil car, and the coil is extracted from the coiler device.

  However, in a coil of a high strength thick steel plate having a large thickness and high strength, as described above, the spring back cannot be suppressed by the bending moment due to the coil's own weight, and as shown in FIG. Winding is loosened at the outer periphery, and the coil is lifted.

  As a result of intensive studies on the technology for suppressing coil winding looseness due to springback of this high-strength hot-rolled steel sheet coil, the present inventors have obtained a high-strength hot-rolled steel sheet guided from a pinch roll to a mandrel, that is, Before being wound on a coiler device (winding device), the coil is loosened by springback by subjecting the hot-rolled steel sheet to appropriate bending / bending processing by means of bending / bending of three rolls. Has been found to be preventable.

Hereinafter, an embodiment of a winding device and a winding method according to the present invention will be described with reference to FIG.
As shown in FIG. 1, the winding device of the present invention includes three bending rolls 9a and 9b having a central axis of rotation between the pinch rolls 3a and 3b and the mandrel 7 in the sheet width direction of the hot-rolled steel sheet. , 9c is provided, and the three rolls are arranged in the order of 9a, 9b, 9c in the steel sheet conveying direction. The rolls 9a to 9c have the same diameter and are free to rotate.
The winding device of the present invention is provided with bending / bending return means, but basically the same configuration as the winding device shown in FIG. 5 except for this means.

The roll 9a and the roll 9c press the upper surface of the hot rolled steel sheet, and the roll 9b presses the lower surface of the hot rolled steel sheet. When the bending / bending process is not performed, the rolls 9a and 9c are retreated upward and the lower part 9b is retracted so as not to contact the steel sheet. When the bending / bending process is performed, the rolls 9a and 9c are The steel plate descends and presses the upper surface of the steel sheet, and 9b rises relatively and presses the lower surface of the steel sheet, so that bending and unbending can be performed. Although the throat guide and apron are not shown in FIG. 1, the throat guide is provided with rolls 9a and 9c, and the apron is provided with roll 9b, unlike the one shown in FIG. 5 in order to provide this bending / rewinding means. Each has a structure. When bending / bending is performed, the apron is fixed and the throat guide is lowered, but the apron may be raised.
Further, as the coiling progresses and the coil diameter increases, the bending / bending return means can move to the pinch rolls 3a and 3b.

  FIG. 2 is a diagram schematically showing the coil winding loosening preventing action by the three rolls of the bending / rewinding means in the present invention, and shows the stress-strain history on the surface on the coil outer peripheral surface side. In FIG. 2, in order to simply explain the operation of the present invention, the material characteristics are shown as an elastic perfect plastic body having a yield stress of σy, and the Bauschinger effect is also omitted.

  First, after the hot-rolled steel sheet 1 passes through the pinch rolls 3a and 3b and then undergoes bending work by the first bending roll 9a, the surface on the coil outer peripheral surface side becomes the inner side of the bending, so that the compressive strain-compressive stress. It becomes a place of. Immediately after that, by undergoing bending back processing by the second bending roll 9b, the tensile stress field is instantaneously changed, and a large tensile strain is generated by bending with a large curvature in the same direction as the coil winding direction. .

  At this time, in the present invention, the curvature to be bent by the second bending roll 9b needs to be larger than the curvature at the time when each position of the hot-rolled steel sheet is wound around the coil. In FIG. Is shown as the target strain. Then, the reverse bending of the hot-rolled steel sheet is again applied to the hot-rolled steel sheet by the third bending roll 9c immediately after that. The positions of the bending rolls 9a, 9b, 9c may be set so as to achieve the target strain. In FIG. 2, as an ideal state, the final strain, that is, the stress in the target strain state is displayed as zero.

  The action of the present invention is that the hot rolled steel sheet 1 is bent more than the curvature of the coil and then bent back, so that the phenomenon opposite to the springback, that is, the elastic deformation in the direction of increasing the bending curvature. It uses the go phenomenon.

  The bending and unbending process of the present invention starts immediately after completion of winding of the front end of the hot-rolled steel sheet and is carried out until the end of winding, but the spring back is particularly noticeable at the outer periphery of the coil. After completion of the winding, the winding operation may be started after the winding operation has progressed to some extent and stabilized until the winding is completed.

  Moreover, in the winding method of the high-strength thick hot-rolled steel sheet, which is the subject of the present invention, ideally, the residual stress inside the sheet thickness becomes 0 as shown schematically in FIG. 2 after winding. However, at the end of winding, since the coil is wound using its own weight so that the vicinity of the tail end of the hot-rolled steel sheet is at the lower side of the coil, even if some residual stress remains good.

Since the coil's own weight suppresses the spring back deformation of the coil, it goes without saying that the coil lifting behavior due to the spring back largely depends on the coil's own weight, but the steel type, coiling temperature, plate thickness Depends on the plate width.
Therefore, in the present invention, including the start timing of the bending / bending / returning process, the bending / rewinding conditions (the descending distances of 9a and 9c) of the hot-rolled steel sheet by the 3-roll type bending / bending / returning means are set to these parameters. It is set according to the feature.
Note that the determination of the bending / unbending conditions may be obtained in advance by experiments, analysis by FEM, or the like based on these parameters. Also, when determining the bending and unbending conditions, it is sufficient to set up the bending conditions based on the manufacturing specifications, and even if a slight error occurs in conditions such as the coiling temperature, the pressing action due to the coil's own weight is achieved. Considering this, the influence of the winding method according to the present invention is almost negligible.

Examples of the present invention will be described below.
The target material is API standard X80 grade, and the thickness (finished plate thickness) is 19 through a rough rolling process and a finishing rolling process of a hot rolling line for a slab having a thickness of 250 mm, a width of 1200, 1500, 1800 mm and a weight of 24 tons. 22 and 25.4 mm, and after cooling to 520 ° C. on a cooling table, it was wound up with a coiler device. The coiler device used in the present invention is as shown in FIG. 1, and the wrapper rolls 5a to 5d have a diameter of 440 mm and the mandrel 7 has an outer diameter of 750 mm.

  The hot-rolled steel sheet speed on the final finish rolling mill exit side, that is, on the cooling table is 150 mpm, and the hot-rolled steel sheet tip 1a enters the coiler at a speed of 150 mpm and starts winding. At this time, the mandrel 7 and the wrapper rolls 5a to 5d are wound at the tip of the hot-rolled steel sheet so that winding is started at a predetermined lead rate with respect to the speed of the hot-rolled steel sheet 1. Acceleration has begun around the missing timing. And the read rate of the mandrel 7 at the start of winding was set to 15%, and the read rate of the wrapper rolls 5a to 5d was set to 25%. After the winding starts, the mandrel 7 and the wrapper rolls 5a to 5d start decelerating, and the speed of the mandrel 7 and the wrapper rolls 5a to 5d synchronizes with the sheet passing speed of the hot-rolled steel sheet 1 when the winding is set to 5 rotations. The speed was reduced to 150 mpm. In this example, bending / bending processing by three rolls of the bending / bending return means was started at this timing, and was carried out until the end of winding.

  The roll diameter of the bending / returning means of the winding device used in this example is φ150 mm, and the arrangement of each roll was determined based on the FEM analysis result performed in advance under each coil condition. And the tail end part 1b of the hot-rolled steel sheet 1 starts decelerating from a position about 20 m before the coiler, and stops rotating at a position where the tail end part 1b of the hot-rolled steel sheet 1 is on the lower side of the coil. The coil car (not shown) that was waiting was raised and the cradle roll 8 was pressed against the lower surface of the coil to fix the vertical position. Thereafter, the wrapper rolls 5a to 5d were separated from the coil, and the diameter of the mandrel was reduced in order to extract the coil.

In this example, the evaluation of the reduction of the coil springback was evaluated based on whether or not the coil was lifted at the moment when the diameter of the mandrel was reduced and whether or not the coil could be extracted from the winding device. Table 1 shows the evaluation results.
The marks ◯, Δ, and X in Table 1 are as follows.
○: No coil lift occurred, and the coil could be removed from the winding device without any problem.
(Triangle | delta): The coil lift was 5 mm or less, and extraction from the coil winding device was possible.
X: A large coil lift (greater than 5 mm) occurred, and the coil could not be removed from the winding device.

  In the comparative example, as for the steel plate (Nos. 10 to 12) having a plate thickness of 25.4 mm, the coil was remarkably lifted at any of the above plate widths, and the coil could not be extracted. Further, when the plate thickness is 22 mm, the plate width is 1500 mm (No. 14), 1800 mm (No. 15) is x, the plate width is 1200 mm (No. 13), Δ, the plate width is 19 mm, the plate width is 1200 mm (No. 16), 1500 mm. In (No. 17), it was ○, but in the case where the plate width was 1800 mm (No. 18), it was ×. As described above, in the comparative example, under the condition that the plate thickness is large and the plate width is wide, the coil floating phenomenon frequently occurs, and the coil cannot be extracted frequently.

In contrast, No. of the present invention example. In each of Nos. 1 to 9, there was no coil lift, and good results were obtained for steel plates having thicknesses of 19 mm, 22 mm, and 25.4 mm at any of plate widths of 1200 mm, 1500 mm, and 1800 mm.
It was confirmed that the coil lift can be suppressed even when the coil lift is generated in the comparative example when the bending and unbending processes are appropriately performed by the three rolls according to the present invention.

1: Hot-rolled steel sheet (rolled material)
1b: End of hot rolled steel sheet 2: Apron 3: Pinch roll 4: Throat guide 5a: No. 1 1 wrapper roll 5b: No. 1 2 wrapper roll 5c: No. 3 wrapper roll 5d: 4 wrapper roll 6: strip guide 7: mandrel 8: cradle roll 9: bending / bending return means 9a: first bending roll 9b: second bending roll 9c: third bending roll

Claims (4)

  A winding device for winding a high-strength, thick hot-rolled steel sheet around a coil, having a pinch roll, a bending / returning means comprising three rolls, a wrapper roll and a mandrel, each roll of the bending / returning means comprising: It has a central axis of rotation in a direction parallel to the sheet width direction of the high-strength hot-rolled steel sheet, and the means applies bending and unbending processes to the hot-rolled steel sheet that is guided by a mandrel through a pinch roll. A winding device for winding a high-strength, thick hot-rolled steel sheet around a coil.   A winding method for winding a high-strength thick-walled hot-rolled steel sheet around a coil by a winding device having a pinch roll, a bending / returning means consisting of three rolls, a wrapper roll and a mandrel, passing through the pinch roll A high-strength, thick-walled hot-rolled steel, characterized in that the hot-rolled steel sheet guided by a mandrel is bent and unbent by bending / bending-back means to reduce winding looseness due to the spring back of the coil. A winding method for winding a steel plate around a coil.   After the end of the high-strength thick steel plate has been wound around the mandrel, it is bent and unbent by means of bending and unbending to reduce winding looseness due to the coil springback, and is wound. A winding method for winding the high-strength thick-walled hot-rolled steel sheet according to claim 2 around a coil. The bending / rewinding condition of the bending / rewinding means is set according to the steel type, the coiling temperature, the coil weight, the plate thickness, and the plate width, according to any one of claims 2 and 3. Winding method for winding a high-strength, thick hot-rolled steel sheet into a coil.