JP2010253482A - Method of winding and carrying away thick high-strength hot-rolled steel plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide methods of winding and carrying away a thick high-strength hot-rolled steel plate, in which the thick high-strength hot-rolled steel plate is wound into a coil in the state where winding slack and lift are reduced with a coiler device, the coil is pulled out of the coiler without hindrance and the coil is carried away to the next stage after turning the coil into the state where springback deformation is reduced. <P>SOLUTION: The coil is pulled out of the coiler without reducing the diameter of a mandrel when winding is finished after applying a processing where the neighborhood of the tail end of the outermost peripheral part of the coil in the state where the coil is held and restrained in the state where there is no winding slack. The coil is bound with one or a plurality of bands and, next, the cooling processing is applied rapidly to the outer peripheral part of the coil with a cooling unit. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for winding and unloading a high-strength thick-walled hot-rolled steel sheet in which a high-strength thick-walled hot-rolled steel sheet is wound around a coil by a coiler device and the coil is unloaded from the coiler device.

  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. Conventionally, as a high-strength pipe, it is a short steel plate that is vertically long in the longitudinal direction. UOE pipes are often used in which the side is formed into a circular shape and then the butt portion is welded in the longitudinal direction to form a pipe. 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 steel sheet is rolled in a hot rolled steel sheet production line for thin sheet rolling and wound into a coil shape to form a hot rolled steel sheet coil, and then the coil is unwound and roll-formed and subjected to medium-frequency welding. There is a growing demand for spiral steel pipes that are manufactured into pipes while welding the welded end of the width of the sheet, while simultaneously forming a sewn tube and a hot-rolled steel sheet into a spiral shape in the longitudinal direction. The hot-rolled steel sheet coil can be manufactured up to about 45 tons. For example, if the thickness is 20 mm and the width is about 1900 mm, the hot-rolled steel sheet has a length of about 151 m, and 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, a hot-rolled steel sheet (sometimes referred to as a hot strip or simply a strip) 1 after passing through a finishing mill of a hot strip mill in a hot-rolled steel sheet production line is usually coiled by a winding device as shown in FIG. Rolled up. That is, the front end portion 1a of the hot-rolled steel sheet travels downward by the pinch roll 3 and is guided between the apron 2 and the throat guide 4, and further, a plurality of wrapper rolls 5 (5a to 5a) disposed around the mandrel. 5d), the arc-shaped strip guide 6 and the mandrel 7 are sequentially bent by the three-point support state and wound around the 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 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. 5) 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. From the coiler device, the mandrel 7 and the wrapper rolls 5a to 5d are released from the coiler while the tail end 1b is restrained from being loosened by its own weight and the coil car is lowered as it is mounted on the cradle roll 8 of the coil car. The coil is pulled out. 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 strip steels The outermost peripheral part is fixed in an annular shape by a band.

  However, in the high strength thick hot rolled steel sheet represented by the line pipe material that is particularly targeted in the present invention, since the cross-sectional area of the steel sheet is large and the strength is very high, a tension for winding up tightly is applied. It will be very difficult to do. 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 mandrel that has been the center of coil rotation is reduced in diameter, the elastic strain component fixed by the mandrel 7 of the coil and the wrapper rolls 5a to 5d is released and a spring back is generated. In addition, the loosening of the outer periphery of the coil becomes significant.

  FIG. 7 shows an example of the winding shape when the coil is pulled out after winding the high-strength thick material, but due to the occurrence of the spring back, the winding is loosened at the outer periphery of the coil. If the coil is loose enough, the coil cannot be lifted and pulled out from the coiler, the coil vibration during transport in the coil car becomes noticeable and the posture becomes unstable, and the band breaks during transport after banding There were problems such as. Even if the coil cools down to room temperature without any problem, the phenomenon that the tail end part of the back end will spring off at the moment of cutting the binding band in the next pipe forming line. ) 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 conventional winding method described above, the tip can be handled by the above-described technique disclosed in Patent Document 1, for example. Winding loosening due to springback is likely to occur at portions other than the tip, particularly the tail end of the strip on the outer periphery side of the coil, and in the vicinity thereof. When the looseness is severe, the coil floats and falls off the coil car when it is pulled out from the coiler (winding device) while mounted on the coil car (coil cart).

  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 and 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 Japan Society for Technology of Plasticity "Bending-Challenge to High Precision-" Corona, January 10, 1995, p. 28 Non-patent document 1 will be described later.

  The present invention has been made in view of the circumstances as described above, and winds a high-strength, thick-walled hot-rolled steel sheet around a coil with a coiler device in a state where winding looseness and lifting are reduced. It is an object of the present invention to provide a winding / unloading method in which the coil can be taken out to the next process in a state in which the coil is pulled out without hindrance and the deformation of the springback is reduced.

The present invention employs the following means in order to solve the above problems.
[1] A method for winding and unloading a high-strength thick-walled hot-rolled steel sheet by winding the high-strength thick-walled hot-rolled steel sheet around a coil with a coiler device and taking out the coil from the coiler device. After performing the process of joining the vicinity of the tail end of the outermost periphery of the coil without reducing the mandrel and holding and restraining the coil without loosening,
The coil is extracted from the coiler unit, and the coil is bundled by one or a plurality of bands, and then the outer periphery of the coil is immediately cooled by a cooling device. Winding / unloading method.
[2] The process of joining the vicinity of the tail end of the outermost peripheral portion of the coil is performed from a part of the plate width end near the contact surface of the outermost layer first and second turns of the coil, or from the first outermost layer winding. n-th roll (
2. The method according to claim 1, wherein a part of the plate width end near the contact surface of the i-th roll and the i + 1-th roll (i + 1 ≦ n) is fixed by welding over n> 2). Winding and unloading method for high-strength, thick hot-rolled steel sheets.
[3] The high strength according to [1], wherein after the cooling treatment, the joint near the tail end of the outermost peripheral portion of the coil subjected to the joining treatment is mechanically removed. A method for winding and unloading thick-walled hot-rolled steel sheets.
[4] After the cooling treatment, a joint portion where the joining treatment is applied to a part of the plate width end in the vicinity of the contact surface of the first and second turns of the outermost layer of the coil, or the first turn of the outermost layer Further, up to the n-th roll (n> 2), the above-mentioned joining process is applied to a part of the plate width end in the vicinity of the contact surface of the i-th roll and the i + 1-th roll (i + 1 ≦ n). The method for winding and unloading a high-strength thick hot-rolled steel sheet according to [2], wherein the part is mechanically removed.
In the present invention, the definition of high strength is X65 or more according to API standards, and the thick hot-rolled steel sheet is intended to have a product thickness of 15 mm or more.

  According to the present invention, a high-strength thick steel plate that is likely to undergo spring-back deformation after winding is maintained without reducing the diameter of the mandrel at the end of winding by the coiler device, and the coil is held in an unwinding state. After performing the process of joining the vicinity of the tail end of the outermost periphery of the coil in a restrained state, the coil is extracted from the coiler device, and the coil is bound by one or a plurality of bands, and then the outer periphery of the coil is immediately attached. By performing a cooling process with the cooling device, the coil can be removed from the coiler device without any hindrance and lifting, and the spring back deformation can be reduced, and the coil can be taken out to the next process. it can.

Explanatory drawing of the winding apparatus and welding situation of a hot-rolled steel sheet according to the present invention The figure which shows embodiment of the coil cooling method by this invention The figure which shows another embodiment of the coil cooling method by this invention. The figure which shows embodiment of the welding part removal method by this invention Diagram showing no coil lift Explanatory drawing of winding device for hot rolled steel sheet The figure which shows the state of coil rising and outer periphery winding looseness

  As a result of intensive studies on techniques for solving the problems caused by springback of this high-strength thick-walled hot-rolled steel sheet coil, the inventors have rapidly cooled the outer peripheral portion of the hot-rolled steel sheet immediately after winding. The present inventors have found that the springback can be reduced by causing thermal contraction to generate a tensile stress in the circumferential direction on the outer periphery of the coil, thereby completing the present invention.

Here, winding by the winding apparatus (coiler apparatus) of the hot-rolled steel sheet in the present invention will be described in detail with reference to FIG. This winding is basically the same as that of a normal hot-rolled steel sheet.
When winding up the front-end | tip part of the hot-rolled steel plate 1 with a coiler apparatus, the peripheral speed of each roll, such as the pinch roll 3, the mandrel 7, and the wrapper roll 5, depends on the thickness and hardness (strength) of the hot-rolled steel plate 1. Thus, the value of the lead rate of 10 to 30% with respect to the conveying speed of the hot rolled steel sheet 1 is controlled, that is, the speed is 10 to 30% faster. At this time, the read rate of the mandrel 7 and the wrapper roll 5 is set to be equal to or higher than the read 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. 6, the number of wrapper rolls is four, but there are also three, and there are generally three to four in the coiler device for hot-rolled steel sheets.

  If the tip of the hot-rolled steel sheet 1 is loosened in the coiler device and is wound in a wavy manner, the subsequent winding cannot be continued, or fortunately the winding up of the tip is successful. Since the subsequent winding part overlaps the outside of the part that is wound and wound, the winding becomes thick and clogging occurs between the housing and cannot be pulled out. Once such a situation occurs, the coiler device The damage to each part 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, the hot rolled steel sheet 1 is used for the purpose of minimizing the looseness of the hot rolled steel sheet 1. From the start of winding the mandrel 7 to the completion of winding, the peripheral speed of each roll such as the pinch roll 3, the mandrel 7, and the wrapper roll 5 has a lead rate, and the hot rolled steel sheet 1 is By winding while being pulled, the tip of the hot-rolled steel sheet 1 is prevented from being loosened and is prevented from being wound and wound.

  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. Winding is performed while performing tension control with the pinch rolls 3 (3a, 3b) close to a desired tension while synchronizing with the above.

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.

  Usually, in a material with a small plate thickness or low strength, as already mentioned, the coil tail ends 1b on the two cradle rolls 8 are bent by the weight of the coil 1 as shown in FIG. The springback is suppressed by the moment, and the coil can be extracted by the coil car 9 after the diameter of the mandrel 7 is reduced.

  On the other hand, as in the case of high-strength, thick-walled pipe materials, which have been increasing in demand in recent years, with a thick steel plate and high-strength steel coil, as described above, the bending moment due to the coil's own weight suppresses springback. An impossible situation occurs.

  Generally, in bending, tensile stress is applied outside the bending and compressive stress is applied inside the bending, and the processing force is removed, that is, the bending moment in the plate thickness section is elastic to a position near zero in the unloading process. Spring back deformation with a changing curvature occurs. In order to reduce this springback deformation, it is known that the amount of deformation until the bending moment becomes zero can be reduced by unloading after applying tensile strain or compressive strain in the longitudinal direction after bending. (Non-Patent Document 1).

  For example, when a tensile strain in the longitudinal direction is applied to a steel plate that is plastically deformed except for the vicinity of the center of the plate thickness by bending, a substantially uniform tensile stress acts over the entire plate thickness by tension, Tensile stress due to tensile deformation is superimposed on the compressive stress acting on the inside of the bend by the bending process, and the compressive stress value on the inside of the bend is reduced. Since the outside of the bend is originally plastically deformed to the tensile side, the tensile stress increases only by a slight amount of work hardening. In such a state, the elastic deformation at unloading is compared with simple bending. The spring back by can be made small.

  The present invention applies this principle to the winding of a high-strength hot-rolled steel sheet coil. Instead of applying an external force after bending, the coil outer periphery is cooled and thermally contracted to cool the coil outer periphery. A large tensile stress is applied to the rolled steel sheet. This is because when the coil is cooled from the outer periphery of the coil, the temperature decrease is larger toward the outer periphery of the coil, and the hot-rolled steel sheet whose temperature has decreased causes heat shrinkage according to the amount of temperature decrease, but the amount of heat shrinkage inside the coil with less temperature decrease. Therefore, elongation strain is generated at the outer peripheral portion of the coil that is largely thermally contracted.

For example, in the case of a high-strength hot-rolled steel sheet coil having a thickness of 25.4 mm and a coil outer diameter of φ1600 mm made of a material having a winding temperature of 500 ° C., a yield stress σ _y of 450 MPa, a Young's modulus E of 160 GPa, The bending strain ε ₁ is about ± 0.016 according to the following equation (1).
ε ₁ = ± h / 2ρ (1)
In the formula (1), h is the thickness of the hot-rolled steel sheet, and ρ is the radius of curvature at the outer periphery of the coil. Further, the outer surface side of the outermost hot-rolled steel sheet is tensile strain and the inner surface side is compressive strain, and the elastic-plastic boundary strain ε ₀ calculated by the following equation (2) is about 0.0028, and the plate thickness It is in a plastic state except for the vicinity of the center.
ε ₀ = ± σ _y / E (2)

In general, since the thermal expansion coefficient of steel is about 1.2 × 10 ⁻⁵ (/ ° C.), for example, by reducing the steel plate temperature by 100 ° C. by cooling, the thermal contraction strain of 0.0012 or 200 ° C. If it is lowered, a thermal shrinkage strain of 0.0028 is generated. This is almost the same as the elastoplastic boundary strain ε ₀ calculated by the equation (2). Actually, the shrinkage deformation is constrained by the internal resistance with a small thermal shrinkage. A large tensile stress is generated in the steel sheet, and the magnitude reaches the yield stress. And since the tensile stress by cooling is added to the stress distribution of the plate | board thickness direction which generate | occur | produced by the bending deformation at the time of winding, the compressive stress which was acting on the inner surface side of bending also changes to the tension side. On the outer surface side of the bending, a tensile stress higher than the yield stress is originally applied by bending, and the tensile stress is only slightly increased by work hardening due to elongation deformation due to cooling.

  The coil outer periphery is preferably cooled in the coiler device after winding from the front end to the tail end of the hot-rolled steel sheet. Must be designed with sufficient consideration for equipment interference with the wrapper rolls 5a to 5d and the strip guide 6, and the next coil can be wound during the cooling time in the coiler device. Therefore, it has problems such as reducing productivity.

  For this reason, in order to solve these problems, the present invention provides a method of cooling the outer periphery of the coil after it is extracted from the coiler device. In order to extract the coil from the coiler device, it is necessary to mechanically fix the springback deformation that occurs when the fixing condition by the wrapper roll 5 and the mandrel 6 is released.

  Normally, the coil loosening restraint that occurs after the coil is extracted from the coiler device is formed by passing one or a plurality of thin steel strip bands in an annular shape to the outermost periphery of the coil with a banding device. Although it is implemented by fixing a band of sheets at the seal portion, it is difficult to incorporate this mechanism into the coiler device due to equipment interference with the wrapper roll 5 and the strip guide 6.

  For this reason, as a means for extracting the coil from the coiler device, the present inventors installed a welding nozzle around the coiler device, and in the vicinity of the tail end portion of the outermost coil portion, the outermost layer first and second rolls Part of the plate width end near the contact surface, or part of the plate width end near the contact surface of the i-th roll and i + 1-th roll (i + 1 ≦ 2) from the outermost layer to the n-th roll (n> 2) By temporarily welding, the coil tail end portion was fixed, and the occurrence of loose winding due to the spring back was suppressed in advance.

  That is, when the winding by the coiler device is finished and the rotation of the mandrel is stopped, the coil is restrained by the wrapper rolls 5a to 5d and the mandrel that has not yet been reduced in diameter, so the coil is not loosened. There is a tightly wound state, and there is no loosening or lifting due to springback deformation. When the coil is in such a state, the above-described welding is performed to fix the coil tail end. Thereafter, the coil is extracted from the coiler device and transferred to a cooling facility to perform a cooling process.

FIG. 1 shows an example of an actual machine configuration according to the present invention.
FIG. 1 shows a coiler that winds a hot rolled steel sheet from the tip to the tail in a coil shape, and then fixes the coil with a mandrel 7 that is not reduced in diameter, wrapper rolls 5a to 5d, and a strip guide 6. Then, after the cradle roll 8 is raised from below the coil and pressed against the coil, a part of the plate width end in the vicinity of the contact surface of the outermost layer 1st winding and the 2nd winding in the vicinity of the tail end of the outermost peripheral portion of the coil. It is the figure which has implemented welding.

In the present embodiment, a welding position is determined by detecting the contact surface positions of the first and second outermost layers using an image processing device (not shown), and the welding nozzle 12 attached to the robot arm 11 is used. After setting at the position, gas welding is performed while moving the nozzle over a length of several tens of mm in the coil circumferential direction by a signal from the control device 10.
In addition, what is necessary is just to use what is generally used for gas welding of steel materials, such as acetylene and propane, as the gas to be used. In this embodiment, welding is performed such that the tail end portion of the hot-rolled steel sheet is located at the lower position of the coil, but the tail end position of the hot-rolled steel sheet is not necessarily limited to the lower position, and welding equipment and The position may be selected in consideration of interference with other equipment.
Moreover, in order to stably fix the coil winding looseness, it is desirable to install a welding device at both ends of the coil and perform welding at substantially the same positions at both ends of the plate width.

This embodiment is intended for automation by using a robot, but of course, a manual welding operation may be used.
In the step of forming a hot-rolled steel sheet into a line pipe, the edge of the plate is trimmed or ground and removed by about a dozen mm before forming, so that the welded portion according to the present invention hardly affects the line pipe product.

  Since the above welding is a temporary fixing to prevent the tail end from being loosened, it is usually sufficient to weld a part of the plate width end near the contact surface of the first and second outermost layers. The length may be about 50 mm to 100 mm. Further, depending on the needs for further increasing the strength and thickness of the hot-rolled steel sheet, the i-th roll and the i + 1-th roll (i + 1) are applied from the first outer roll to the n-th roll (n> 2) as necessary. A part of the plate width end in the vicinity of the contact surface of + 1 ≦ n) may be welded, and the number of welded portions may be appropriately increased and fixed.

  After the welding is completed, the welding nozzle is retracted, the wrapper roll 5 and the strip guide 6 are opened, the mandrel is reduced in diameter, the normal coil extraction operation is performed, and one banding device adjacent to the coiler device is used. A plurality of bands are attached to the outermost periphery of the coil in an annular shape to bind the coils. And before the temperature of a coil falls, a coil is immediately conveyed to cooling equipment and a coil outer peripheral part is cooled to predetermined temperature.

  The coil cooling action according to the present invention is more effective as the temperature difference between the coil outer periphery and the coil increases, so it is desirable to cool the outer periphery with the coil temperature being high. For this reason, it is desirable to install the coil cooling zone adjacent to the coiler facility or in the coil yard. At this time, the tensile strain necessary for reducing the springback, that is, the temperature drop due to the cooling of the outer peripheral portion, is the strength of the hot-rolled steel plate, the plate thickness, the outside of the coil, based on the relationship of the equations (1) and (2). Since the influence of the diameter, the target winding temperature (that is, the strength at the time of winding) and the like are greatly affected, the springback reduction conditions based on these parameters may be determined in advance by experiments and analysis.

  In addition, the high-strength hot-rolled steel sheet material for line pipes, which is the subject of the present invention, is very thick with a thickness of 15 mm or more. Therefore, in order to increase the temperature difference between the outer periphery of the coil and the inside of the coil, it is cooled with a large flow rate. It is desirable to perform strong cooling using water and to cool the outer periphery of the coil uniformly.

FIG. 2 and FIG. 3 show an example of an embodiment according to the present invention. FIG. 2 shows that a coil is set on a rotatable mandrel 7 'and the outer peripheral portion is cooled by a cooling nozzle 14 while rotating the coil. . FIG. 3 shows the cooling of the outer periphery of the coil by the cooling nozzle 14 in a state where the coil is set in the coil car 9. In this embodiment, the cooling nozzle 14 is also installed in the coil car 9, and the coil The lower area is also cooled. The cooling process of the outer periphery of the coil according to the present invention has the effect of reducing the loosening of the winding due to the tightening in addition to the effect of reducing the spring back as described above. is there. 2 and 3, reference numeral 13 denotes a band. Since the spring back is reduced after cooling the coil outer periphery, the band is removed before or after removal of the welded portion described later in the next process (here, the pipe forming line) in which the coil is conveyed, Alternatively, it is removed before being transferred to the next process.

  In the pipe forming line of the next process, it is necessary to remove the temporary weld in order to unwind and pay out the coil. However, the spring back is greatly reduced in the coil that has been cooled on the outer periphery in the cooling zone. Therefore, a temporary weld is not necessary. For this reason, in Claim 3 of this invention, it is prescribed | regulated that this welding part should be removed by mechanical means, such as a grinder. FIG. 4 shows an example of this embodiment of the removal work. The present embodiment is an example in which a welded portion is ground and removed using a cup grindstone-type grinder 15.

In addition, this embodiment is an example in which automation using a robot is considered from the viewpoint of productivity. Moreover, the removal operation of the welded portion may be performed immediately after the coil cooling process or before the coil discharging process in the next process, and is not particularly defined in the present invention.
In addition, in this embodiment, although the process of shape | molding a line pipe was mentioned as a next process, it is not restricted to this.

Examples of the present invention will be described below.
The target material is API standard X80 grade, and the thickness of 250 mm, width 1850 mm, length 9090 mm of slab (weight 33 tons) undergoes hot rolling line rough rolling process, finish rolling process and thickness 16-25. After finishing to 4 mm and cooling to 520 ° C. on a cooling table, it was wound up by a coiler device.
The coiler device used in the present invention is as shown in FIG. 1, the wrapper rolls 5a to 5d have a diameter of 440 mm, and the mandrel 7 has an outer diameter of 750 mm. The diameter is a coil of φ1858 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. The tail end 1b of the hot-rolled steel sheet 1 started decelerating from a position about 20 m before the coiler, and the rotation was stopped at a position where the tail end 1b of the hot-rolled steel sheet 1 was on the coil lower side. At this time, the wrapper rolls 5a to 5d and the strip guide press the outer periphery of the coil, and the mandrel is not reduced in diameter.
Then, the cradle roll 8 provided in the coil car 9 that was waiting under the coil was raised and pressed against the lower surface of the coil to fix the vertical position.

The subsequent processing is the same as that of the present invention. 1-4 and Comparative Example No. Different from 5-8.
This invention No. About 1-4, the contact surface position of the outermost layer 1st roll and 2nd roll in the coil lower position was detected with the image processing apparatus which is not shown in figure. After this detection information is transmitted to the robot arm control device 10, the motion condition of the arm is calculated, and the motion of the robot arm is controlled by the command. Then, the contact surface of the first and second windings of the outermost layer is welded over a length of about 80 mm while moving the ignited welding nozzle attached to the tip of the arm at a speed of 5 mm per second in the circumferential direction. It was.
Two welding systems were installed at approximately the same position in the vicinity of both sides of the coil, and the welding operation was performed at approximately the same position at the width ends of both plates.

After the welding operation is completed, the wrapper rolls 5a to 5d are retracted from the coil, the diameter of the mandrel 7 is reduced for coil extraction, the coil is extracted from the coiler device, mounted on the cradle roll 8, and conveyed by the coil car 9. Banding processing was performed to bind the coils with a band of thin steel strip in an adjacent banding device.
And it conveyed to the coil water cooling yard installed in the coil yard entrance vicinity by the conveyor, and the coil outer periphery part was strongly cooled with the coil water cooling apparatus shown in FIG.

  In order to suppress the springback under this condition based on the previous FEM analysis, the temperature drop at the outermost periphery of the coil, that is, the difference between the temperature at winding and the temperature after strong cooling is about 350 ° C. As a result, the amount of temperature decrease due to coil outer periphery cooling in the present invention was set to 350 ° C. The coil cooling time for realizing the main cooling temperature was about 60 seconds.

After the water cooling treatment of the coil was completed, the coil was transported to a weld removal device (FIG. 4) installed at the coil cooling yard outlet by a conveyor, and the weld was completely removed. Then, after cooling a coil to normal temperature in a coil yard, it conveyed to the spiral pipe factory, removed the band, and used for shaping | molding of a spiral pipe.
In contrast, Comparative Example No. Nos. 5 to 8 of the present invention. In 1-4, the above-described welding and cooling by the coil water cooling device are not performed. Therefore, Comparative Example No. In Nos. 5 to 8, normal coiling and extraction from the coiler device were performed by the coiler device. Then, what could be extracted was directly subjected to a spiral pipe forming process (note that the band was removed in this process).

Table 1 shows the evaluation results in this example.
・ Extracting from the coiler device by hot rolling ("Hot rolling coiler extraction" in Table 1)
In the comparative example, No. 16 having a plate thickness of 16 mm. In No. 8, as a result of the springback being held down by the dead weight of the coil, it was possible to extract it from the coiler without any problem (O rating). No. with a plate thickness of 22 mm or more. 5 and no. No. 6, the spring back when extracting the coil is large, the coil floats up as soon as the diameter of the mandrel is reduced, and the coil inner diameter portion is in strong contact with the mandrel. Gas cutting treatment was performed (x evaluation). In addition, No. 19 mm thick. In Fig. 7, it was difficult to extract the coil from the coiler due to the lifting of the coil. However, when the mandrel was expanded and contracted several times based on operational experience, the coil was finally extracted from the hot-rolled coiler (coiler device).

  On the other hand, the present invention No. In Nos. 1 to 4, since the outer peripheral tail end of the coil was welded, the coil was not lifted by the spring back, and the coil could be extracted.

-About coil tail end jumping in the pipe forming process ("Pipe forming process tail end jumping" in Table 1)
This invention No. which could be extracted from a coiler by hot rolling. 1-4 and Comparative Example No. The coils 7 and 8 were subjected to a spiral pipe forming process, and the behavior of the coil tail end jumping up by a springback immediately after cutting the band in a state where it was set on an uncoiler was observed. The present invention No. 1 was cooled by a coil water cooling device. In 1-4, the jumping of the tail end part was hardly seen, and all were (circle) evaluation. On the other hand, in the comparative example, No. 19 having a plate thickness of 19 mm. In No. 7, the tail end jumped greatly, and a large loosening occurred from the outermost circumference to the third roll (× evaluation). In addition, No. 16 having a plate thickness of 16 mm. In No. 8, a slight jumping of the tail end portion occurred, but no loosening of the outer peripheral portion occurred (Δ evaluation).

  This invention No. 1-4, a high-strength, thick-walled hot-rolled steel sheet can be wound around a coil with a coiler device in a state where winding looseness and lifting are reduced, and the coil can be pulled out from the coiler device without hindrance, and springback deformation can be performed. It was confirmed that the coil could be taken out for pipe forming in the next process in a reduced state.

1: Hot rolled steel sheet coil 2: Apron 3a, 3b: Pinch roll 4: Throat guide 5a-5d: Wrapper roll 6: Strip guide 7, 7 ': Mandrel 8: Cradle roll 9: Coil car 10, 10': Robot arm control Apparatus 11, 11 ': Robot arm 12: Welding nozzle 13: Band 14: Cooling nozzle 15: Grinder

Claims (4)

  A high strength thick hot rolled steel sheet is wound around a coil by a coiler device, and the coil is taken out from the coiler device. Without applying coil, the coil is pulled out from the coiler device, and then one or more bands are applied. A method for winding and carrying out a high-strength thick-walled hot-rolled steel sheet, characterized in that the coils are bundled together and then the outer periphery of the coil is immediately cooled by a cooling device.   The process of joining the vicinity of the tail end of the outermost periphery of the coil is the nth turn from the part of the plate width end near the contact surface of the first and second turns of the coil, or the first turn of the outermost layer. The part of the plate width end in the vicinity of the contact surface of the i-th roll and the i + 1-th roll (i + 1≤n) is fixed by welding over (n> 2). Winding and unloading method for high-strength, thick-walled hot-rolled steel sheets.   2. The high-strength thick heat according to claim 1, wherein after the cooling treatment, the joint portion near the tail end portion of the outermost peripheral portion of the coil subjected to the joining treatment is mechanically removed. Winding and unloading method for rolled steel sheets.   After the cooling treatment, the coil is subjected to n turns from the joining portion in which the joining treatment is applied to a part of the plate width end in the vicinity of the contact surface of the first and second turns of the outermost layer of the coil or the first turn of the outermost layer. Mechanically connecting the joint portion where the above-mentioned joining treatment is applied to a part of the plate width end in the vicinity of the contact surface of the i-th roll and the i + 1-th roll (i + 1 ≦ n) over the eyes (n> 2) The method for winding and unloading a high-strength thick-walled hot-rolled steel sheet according to claim 2, wherein

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