JP2019038035A - Hat-shaped steel sheet pile, manufacturing method of hat-shaped steel sheet pile, and manufacturing facility therefor - Google Patents

Abstract

Kind Code: A1 A hat-shaped steel sheet pile cut to a predetermined product length regardless of whether it is hot or cold after rolling has a favorable shape free from shape defects such as "trumpet deformation" and "reverse trumpet deformation" at the ends. To provide a hat-shaped steel sheet pile. A hat-shaped steel sheet pile 1 is composed of a web portion 2, a flange portion 3, an arm portion 5 and a joint portion 4, and the joint portion 4 or the arm portion 5 has a residual stress maximum value σg and the minimum residual stress value σf of the flange portion 3 is a residual stress difference Δσ (=σg−σf) of 0 MPa or more and 60 MPa or less. [Selection drawing] Fig. 7

Description

  TECHNICAL FIELD The present invention relates to a hat-shaped steel sheet pile, a manufacturing method thereof, and a manufacturing facility, and in particular, a hat-shaped steel sheet pile capable of obtaining an end portion having excellent dimensional accuracy after sawing, a manufacturing method of a hat-shaped steel sheet pile, and manufacturing thereof Regarding equipment.

Shaped steel manufactured by hot rolling may be warped after cooling due to temperature differences due to differences in thickness of sections or differences in cooling conditions, or when hot sawing is performed after hot rolling. The residual stress generated in the cross-section is released by the hot saw cut part, so that end deformation occurs.
Patent Document 1 relates to a method for restraining cooling of a shape steel. In order to eliminate a warp caused by non-uniform temperature in a cross section generated during hot rolling, the shape steel being cooled based on the shape steel temperature at the start of restraint cooling. It is described that the constrained cooling conditions are selected so that warpage does not occur based on estimation of temperature, transformation point rate, and the like.
When end deformation occurs in the shape steel, it is necessary to correct the end shape after sawing. However, in leveler correction, it is difficult to correct because the end in the longitudinal direction cannot be reduced. On the other hand, if press correction is used, correction is possible, but the production efficiency decreases.

Patent Document 2 relates to a method for adjusting the shape of an end of a steel sheet pile or the like in a rolling line. When a U-shaped steel sheet pile having a joint at the tip of the flange is rolled, the thickness of the web or flange is reduced in the cooling process after rolling. Due to the difference, the flange is cooled faster than the web, and the longitudinal ends that are prone to form defects due to the release of thermal stress due to sawing, etc. It is described that the flange root portion (corner portion) is cooled to be within a dimensional tolerance.
Patent Document 3 relates to a method for controlling an end shape of a shape steel, and measures the temperature of the outer surface of the flange or web immediately after the hot sawing, and obtains cooling based on the correlation between the temperature and the end bend. It is described that forced cooling is performed during and / or after sawing so that the reference temperature is reached.

JP-A-2-15816 JP-A-53-81464 JP-A-55-139105

  By the way, as shown in FIG. 11 (a) as a whole of the cross-sectional shape, the web part 2, the flange part 3, the joint part 4, and the arm part 5 are provided between the flange part 3 and the joint part 4. In the case of the hat-shaped steel sheet pile 1, the cross-sectional dimension is larger than that of the U-shaped steel sheet pile because of the arm portion 5. For this reason, in the hat-shaped steel sheet pile 1, the residual stress generated after cooling due to non-uniform temperature in each section in the cross-section at the time of rolling finish has a great influence on the cross-sectional shape. When the hat-shaped steel sheet pile 1 is cut in the width direction), the deformation of the end due to the residual stress becomes larger, and in some cases, the dimensional tolerance may be removed. FIG. 11 (b) shows a state where the joint portion 4 of the hat-shaped steel sheet pile 1 is enlarged, and FIG. 11 (c) shows a state where the joint portions 4 of the hat-shaped steel sheet pile 1 are fitted together. .

  FIG. 12 is a schematic view of the deformation that occurs at the end of the hat-shaped steel sheet pile 1, so-called “trumpet deformation” (see FIG. 12A), in which the left and right joint portions 4 spread outward and warp upward. In addition, the “reverse trumpet deformation” (see FIG. 12B) in which the left and right joint portions 4 are narrowed inward and warped downward, or one of the left and right joint portions 4 is “trumpet deformation” and the other is “reverse” It may be deformed into a shape called “trumpet deformation”.

The technique described in Patent Document 1 is a technique for preventing the warp in the vertical direction of the steel sheet pile, and does not prevent the trumpet deformation at the end of the product. In addition, in order to perform constrained cooling, a very large capital investment is required.
The technique described in Patent Document 2 is a technique for cooling the flange base of the U-shaped steel sheet pile during hot sawing after rolling, and is not a technique that can be applied to the hat-shaped steel sheet pile as it is. In particular, the hat-shaped steel sheet pile has a more complicated shape and larger size (full width dimension) than the U-shaped steel sheet pile, so that the number of rolling passes increases and the temperature during hot sawing becomes very low. For this reason, this technology is not expected to be effective. In addition to the hot sawing, the steel sheet pile is often sawed to a predetermined length in the cold, but this technique cannot cope with the sawed portion of the cold-sawed steel sheet pile at all.

  The technique described in Patent Document 3 is a technique for preventing deformation of the end portion that is caused by the temperature difference between the inner and outer surfaces of the steel sheet pile during hot sawing, not the temperature difference between the inner and outer surfaces, It cannot be applied to the end deformation of the hat-shaped steel sheet pile generated by the temperature difference of each part. In addition to the hot sawing, the steel sheet pile is often sawed to a predetermined length in the cold as well as in Patent Document 2, but this technique is applied to the sawed portion of the cold-sawed steel sheet pile. Can not cope at all.

  Therefore, the present invention has been made in view of such problems, and relates to a hat-shaped steel sheet pile, in which a hat-shaped steel sheet pile cut into a predetermined product length regardless of whether it is hot or cold after rolling. Providing a hat-shaped steel sheet pile having a good shape that does not have a defective shape such as “trumpet deformation” and “reverse trumpet deformation” at the end, and a method for producing a hat-shaped steel sheet pile that realizes it at low cost. Furthermore, the present invention provides a manufacturing facility for a hat-shaped steel sheet pile capable of evaluating manufacturing conditions for suppressing the above-described defective shape, and further, a hat-shaped steel sheet pile capable of suppressing the above-mentioned defective shape based on this evaluation. The purpose is to provide manufacturing equipment.

  According to one aspect of the present invention, a hat-shaped steel sheet pile composed of a web portion, a flange portion, an arm portion, and a joint portion, the residual stress maximum value σg of the joint portion or the arm portion and the residual stress minimum value of the flange portion A hat-shaped steel sheet pile having a residual stress difference Δσ (= σg−σf), which is a difference from σf, of 0 MPa or more and 60 MPa or less is provided.

  According to one aspect of the present invention, a hat-shaped steel sheet pile composed of a web portion, a flange portion, an arm portion, and a joint portion is shaped into the shape of the hat-shaped steel sheet pile by hot rolling, and then cut in the width direction. In the manufacturing method of the hat-shaped steel sheet pile, the minimum temperature Tf of the flange portion and the joint portion or the arm at the same time after the hot rolling is finished and before the temperature of the web portion drops to 500 ° C. The difference from the maximum temperature Tg of the part is defined as a temperature difference ΔT (= Tg−Tf), and the relationship between the temperature difference ΔT and the amount of bending at the end of the cut surface after the cutting is determined. There is provided a manufacturing method of a hat-shaped steel sheet pile, wherein the joint portion is cooled in rolling in a final hole mold of a finish rolling mill so as to obtain a range of ΔT that allows the bending amount to be within an allowable value. The

  According to one aspect of the present invention, a hat-shaped steel sheet pile composed of a web portion, a flange portion, an arm portion, and a joint portion is shaped into the shape of the hat-shaped steel sheet pile by hot rolling, and then cut in the width direction. In the manufacturing method of the hat-shaped steel sheet pile, the minimum temperature Tf of the flange portion and the joint portion or the arm at the same time after the hot rolling is finished and before the temperature of the web portion drops to 500 ° C. The difference between the maximum temperature Tg of the joint portion is the temperature difference ΔT (= Tg−Tf), and the difference between the maximum residual stress value σg of the joint or arm and the minimum residual stress value σf of the flange portion is the residual stress difference Δσ (= σg). −σf), and a relationship between the temperature difference ΔT and the residual stress difference Δσ is determined, and a finish rolling mill is obtained so that a range of ΔT that allows the residual stress difference Δσ to be 0 MPa or more and 60 MPa or less is obtained based on this relationship. In the rolling in the final hole mold Method for producing a hat-shaped steel sheet pile, characterized in that for cooling of the hand portion is provided.

  According to one aspect of the present invention, a hat-shaped steel sheet pile composed of a web portion, a flange portion, an arm portion, and a joint portion is shaped into the shape of the hat-shaped steel sheet pile by hot rolling, and then cut in the width direction. In the manufacturing method of the hat-shaped steel sheet pile, the joint portion is cooled in rolling in the final hole shape of the finish rolling mill, and the flow rate Q per unit time of the refrigerant for performing the cooling is set at the time of rolling by the finishing mill. A relationship between the value Q / V divided by the rolling speed V and the bending amount of the cut end portion after cutting is determined in advance, and the value Q / V that makes the bending amount within an allowable range based on the relationship. And a flow rate Q per unit time of the refrigerant is adjusted so that the value Q / V falls within the set range in accordance with the change of the rolling speed V. A method for manufacturing a sheet pile is provided.

  According to one aspect of the present invention, a hot rolling mill that forms a hat-shaped steel sheet pile composed of a web portion, a flange portion, an arm portion, and a joint portion into the shape of the hat-shaped steel sheet pile by hot rolling; In a production facility for a hat-shaped steel sheet pile having a cutting device for cutting the hat-shaped steel sheet pile obtained by the hot rolling in the width direction, the joint portion is provided in a guide of a finish rolling mill of the hot rolling mill. A joint part cooling device for cooling, the joint part cooling device is capable of adjusting a flow rate Q per unit time of a refrigerant for cooling the joint part, and the finish rolling mill is capable of adjusting a rolling speed V, There is provided a production facility for a hat-shaped steel sheet pile having recording means for recording the results of the flow rate Q and the rolling speed V.

  According to the hat-shaped steel sheet pile according to the present invention, deformation of the end of the longitudinal portion when being cut hot or cold is suppressed, that is, a predetermined product regardless of whether it is hot or cold after rolling. Provided is a well-shaped hat-shaped steel sheet pile in which the end of the hat-shaped steel sheet pile cut into lengths does not have a shape defect of “trumpet deformation” or “reverse trumpet deformation”. Moreover, according to the manufacturing method of the hat-shaped steel sheet pile according to the present invention, a hat-shaped steel sheet pile that realizes a hat-shaped steel sheet pile capable of suppressing deformation of the end of the longitudinal portion when it is cut hot or cold at low cost. A manufacturing method is provided. In addition, according to one aspect of the present invention, it is possible to evaluate the manufacturing conditions for suppressing deformation of the end portion of the longitudinal portion when it is sawed hot or cold, and based on this evaluation, the above-mentioned defective shape is obtained. A manufacturing facility for a controllable hat-shaped steel sheet pile is provided.

It is the top view which showed the manufacturing line of the hat-shaped steel sheet pile which manufactures the hat-shaped steel sheet pile concerning one Embodiment of this invention. It is a front view which shows the hole shape of a finish rolling mill. It is a figure which shows the front guide installed in the front of K1 hole type | mold, a joint part cooling device, and a web part cooling device, (a) shows a front view, (b) shows a side view. It is a schematic diagram which shows the equipment structure of the cooling control of a joint part, and the cooling control of a web part. It is a graph which shows an example of the temperature distribution of the full width direction of the hat-shaped steel sheet pile after finish rolling. It is a graph which shows an example of the width direction distribution of the longitudinal direction residual stress of a hat-shaped steel sheet pile. It is a graph which shows the relationship between residual-stress difference (DELTA) (sigma) and edge part deformation amount (bending amount of a joint part). It is a graph which shows the relationship between temperature difference (DELTA) T and an edge part deformation amount (bending amount of a joint part). It is a graph which shows the relationship between temperature difference (DELTA) T and residual stress difference (DELTA) (sigma). It is a graph which shows the relationship between Q / V and an edge part deformation amount (bending amount of a joint part). A hat-shaped steel sheet pile is shown, (a) is the figure which shows the whole cross-sectional shape of a hat-shaped steel sheet pile, (b) is a figure which shows the state which expanded the joint part of the hat-shaped steel sheet pile, (c) is a hat. It is a figure which shows the state which the coupling parts of a shaped steel sheet pile fit. It is a schematic diagram which shows a deformation | transformation of the longitudinal direction edge part of a hat-shaped steel sheet pile, (a) shows a trumpet deformation, (b) shows a reverse trumpet deformation. It is a schematic diagram which shows the state with a curvature (upward curvature) in a hat-shaped steel sheet pile. It is a graph which shows the relationship between web cooling water amount Qw / rolling speed V, and curvature amount S.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Each drawing is schematic and may be different from the actual one. Further, the following embodiments exemplify apparatuses and methods for embodying the technical idea of the present invention, and the configuration is not specified as follows. That is, the technical idea of the present invention can be variously modified within the technical scope described in the claims.

FIG. 1 is a plan view showing a production line for a hat-shaped steel sheet pile. The production line for the hat-shaped steel sheet pile includes a heating furnace 10, a plurality of hot rolling mills, that is, a rough rolling mill 11, an intermediate rolling mill 12, and a finish rolling mill 13. The production line for the hat-shaped steel sheet pile includes a hot sawing device 14 on the downstream side of the finish rolling mill 13 of the hot rolling mill. The intermediate rolling mill 12 is configured by arranging two rolling mills in tandem.
A slab or bloom as a raw material is heated to a predetermined temperature in a heating furnace 10, and hot rolling is performed in the order of a rough rolling mill 11, an intermediate rolling mill 12, and a finishing rolling mill 13 to form a hat shape shown in FIG. Finished in product shape. The hot sawing device 14 is for hot cutting a product extended by rolling into a predetermined length.

  Each rolling mill is engraved with a plurality of perforations. For example, as shown in FIG. 2, in the finishing mill 13, two perforations K2, K1 are engraved on the upper rolling roll 21 and the lower rolling roll 22. Has been. The K1 hole mold is a hole mold for final rolling, and claw bending and forming rolling are performed simultaneously. The finish rolling is a reverse rolling of 3 passes in total, and the K2 hole type rolling is the first pass rolling from the front surface (left side in FIG. 1) to the rear surface (right side in FIG. 1). Rolled. K1 hole rolling is performed by reverse rolling in the second pass, and is rolled from the rear surface of the finish rolling mill 13 toward the front surface side. The third pass of the finish rolling is a dummy rolling pass in which the material to be rolled is passed from the front surface to the rear surface of the finish rolling machine 13 but no reduction is performed.

  FIG. 3 is a schematic view showing the front guide 23 installed on the front surface of the K1 hole type, and the joint part cooling device 25 and the web part cooling device 26 installed in the front guide 23. Fig.3 (a) is the front view seen from the rolling direction, FIG.3 (b) is a side view. The front guide 23 includes an upper guide 23 a and a lower guide 23 b that guide the web portion 2, the flange portion 3, and the arm portion 5 of the hat-shaped steel sheet pile. A joint part cooling header 25a is disposed in the upper guide 23a, and a joint part cooling nozzle 25b is provided in the joint part cooling header 25a. The joint portion cooling header 25a extends in the rolling direction (left and right direction in FIG. 3B), and the joint portion cooling nozzle 25b is located at a position facing the joint portion 4 of the hat-shaped steel sheet pile 1 at the joint portion cooling header 25a. A plurality are arranged along the extending direction. And the joint part cooling nozzle 25b can eject a refrigerant | coolant toward the joint part 4, and the joint part 4 of a hat-shaped steel sheet pile is cooled by this joint part cooling nozzle 25b. The joint portion cooling header 25a, the joint portion cooling nozzle 25b, the joint portion cooling water flow rate adjustment valve 25e, which will be described later, and the arithmetic unit 30 that adjusts the opening degree of the joint portion cooling water flow rate adjustment valve 25e constitute the joint portion cooling device 25. doing. In this figure, the joint part cooling device 25 is arranged on the upper guide 23a and the joint part 4 is cooled from above. However, the joint part cooling header 25a and the joint part cooling nozzle 25b are arranged on the lower guide 23b. The joint portion 4 may be cooled. Further, the portion to be cooled most in the joint portion 4 is the protrusion 4a (see FIG. 11B) of the joint portion 4, and the protrusion 4a is used as a center and extends to the claw portion 4b and the arm portion 5. Cooling may be performed. Further, the joint cooling device 25 may be provided on the rear guide 24 (see FIG. 4).

  The upper guide 23a is also provided with a web upper surface cooling header 26a and a web upper surface cooling nozzle 26b, so that the upper surface of the web portion 2 of the hat-shaped steel sheet pile 1 can be cooled. That is, the web upper surface cooling nozzle 26b is disposed at a position facing the upper surface of the web portion 2 of the web upper surface cooling header 26a, and can inject the refrigerant onto the upper surface of the web portion 2. The lower guide 23b is provided with a web lower surface cooling header 26c and a web lower surface cooling nozzle 26d, and cools the lower surface (back surface) of the web portion 2 of the hat-shaped steel sheet pile 1. That is, the web lower surface cooling nozzle 26d is disposed at a position facing the lower surface of the web portion 2 of the web lower surface cooling header 26c, and can inject the refrigerant onto the lower surface of the web portion 2. The web upper surface cooling header 26a and the web lower surface cooling header 26c extend in the rolling direction (left and right direction in FIG. 3B) similarly to the joint cooling header 25a, and the web upper surface cooling nozzle 26b and the web lower surface cooling. A plurality of nozzles 26d are arranged in the header extending direction so that a predetermined cooling capacity can be exhibited. Web upper surface cooling header 26a, web upper surface cooling nozzle 26b, web lower surface cooling header 26c, web lower surface cooling nozzle 26d, web upper surface cooling water flow rate adjustment valve 26e, web lower surface cooling water flow rate adjustment valve 26f, which will be described later, The arithmetic unit 30 that adjusts the opening degree of the web upper surface cooling water flow rate adjustment valve 26e and the web lower surface cooling water flow rate adjustment valve 26f constitutes the web part cooling device 26. The web part cooling device 26 may be provided on the rear guide 24.

  FIG. 4 is a schematic diagram showing an equipment configuration that enables cooling control of the joint portion 4 and cooling control of the web portion 2 during the final hole-type K1 rolling of the finish rolling mill 13. The left and right joint cooling headers 25a, web upper surface cooling headers 26a, and web lower surface cooling headers 26c (not shown in FIG. 4) provided on the upper guide 23a of the front guide 23 of the hole mold K1 are respectively provided with cooling water pipes. To the cooling water pump 29. Each of the cooling water pipes has a flow rate adjusting valve 25e (joint portion cooling water flow rate adjusting valve 25e), 26e (web upper surface cooling water flow rate adjusting valve 26e), 26f (web lower surface cooling water flow rate adjusting valve 26f: not shown). The flow rate adjusting valves 25e, 26e, and 26f can individually adjust the cooling water supply amount to the cooling headers 25a, 26a, and 26c, that is, the flow rate Q per unit time. The calculation device 30 adjusts the opening of the flow rate adjusting valves 25e, 26e, and 26f.

  The arithmetic unit 30 adjusts the opening degree of the flow rate adjusting valves 25e, 26e, and 26f and sends a rotational speed command signal to the mill motor 13a of the finish rolling mill 13 to control the rolling speed of the hat-shaped steel sheet pile 1 by the finish rolling mill 13. Also do. The arithmetic unit 30 is a mill motor for adjusting the finish rolling speed V (hereinafter also simply referred to as the rolling speed V) of the finish rolling mill 13 based on the rolling condition information of the material to be rolled from a host computer (not shown). A rotation speed command signal is sent to 13a. The rolling speed V (m / sec) is adjusted based on whether or not bending occurs and wrinkles such as seizure occur, in addition to making the rolling speed faster than the steady portion when biting. The arithmetic unit 30 adjusts the opening degree of the flow rate adjusting valves 25e, 26e, and 26f, and unit time of the refrigerant (water in this embodiment) that cools the upper surface of the joint portion 4 and the web portion 2 and the lower surface of the web portion 2. It functions as a flow rate control means for adjusting the per unit flow rate Q (liter / second). When the rolling speed V changes, the flow rate Q per unit time of the refrigerant for exhibiting a certain amount of cooling capacity changes. Therefore, in this embodiment, the arithmetic unit 30 changes the cooling header 25a according to the change of the rolling speed V. , 26a, 26c, the flow rate Q per unit time of the cooling water supplied is adjusted. Specifically, the arithmetic unit 30 sets the flow rate adjusting valves 25e, 25e, so that the value Q / V obtained by dividing the flow rate Q of the cooling water supplied to each cooling header per unit time by the rolling speed V is within a certain range. The opening degree of 26e, 26f is adjusted, and the flow rate Q of the cooling water to each cooling header 25a, 26a, 26c is controlled.

  The specific numerical value range of Q / V is the relationship between the value of Q / V and the bending amount of the end of the cut surface after being cut by the hot sawing device 14 for the joint cooling device 25, or Q / V The relationship between the value of V and the temperature difference ΔT (= Tg−Tf) between the minimum temperature Tf of the flange portion and the maximum temperature Tg of the joint portion 4 or the arm portion 5 at a predetermined time after finish rolling is determined in advance. From any one of the relations, it is set as a Q / V range where the bending amount is within an allowable range or a Q / V range where the temperature difference ΔT is within a predetermined range. Details of the reason why the bending of the end of the cut surface can be suppressed by adjusting the flow rate Q of the cooling water from the joint cooling device 25 so that Q / V is in a certain range will be described later.

  The reason for cooling the web part 2 by the web part cooling device 26 is to prevent warping during natural cooling on the CB (cooling bed) after rolling, as will be described later. Therefore, for a specific numerical value range of Q / V for the web part cooling device 26, the relationship between the value of Q / V and the amount of warpage of the hat-shaped steel sheet pile on the cooling bed is determined in advance. Therefore, the Q / V range is set so that the warpage amount is within the allowable range.

  The hat-shaped steel sheet pile 1 subjected to finish rolling by the finish rolling mill 13 is sent to the downstream side by the table roller 35 arranged along the conveying direction of the hat-shaped steel sheet pile 1, but downstream of the finish rolling mill 13. A thermometer 31 is arranged on the side, and this thermometer 31 is used to measure the temperature profile in the width direction of the hat-shaped steel sheet pile 1 after finish rolling, that is, after rolling by the final hole mold K1. It is possible. The measurement result of the temperature profile by the thermometer 31 is sent to the arithmetic unit 30. When the above-described temperature difference ΔT (= Tg−Tf) is desired to be within a predetermined range, the arithmetic unit 30 compares ΔT obtained from the temperature measurement result with the target ΔT, and at the time of rolling the next material, the target ΔT is The opening setting command to the flow rate adjusting valves 25e, 26e, and 26f of the joint cooling device 25 and the web cooling device 26 and the rotational speed command to the mill motor 13a of the finishing mill 13 are corrected so as to be obtained.

  The flow rates of the coolant (cooling water in the present embodiment) on the surfaces of the left joint portion 4, the right joint portion 4, and the web portion 2 can be set individually. Since the joint shape of the hat-shaped steel sheet pile 1 is an asymmetric shape on the left and right as shown in FIG. 11B, a temperature difference is likely to occur between the left and right joint parts 4, but the cooling water flow rate of the left and right joint parts 4 By setting each individually, it is possible to cope with the case where deformation of only one joint portion becomes a problem.

  Moreover, the cooling of the surface of the web part 2 is effective in suppressing the occurrence of warping during natural cooling on a CB (cooling bed) after rolling. When the warpage on the CB is large, troubles are caused in the conveyance of the product in the CB, and in the roller correction performed after cooling to room temperature, the product does not get caught in the roll. By cooling the surface of the web part 2 as described above, such a problem can be suppressed.

  The arithmetic unit 30 has a recording means for recording the actual flow rate Q and the rolling speed V per unit time of the cooling water supplied to the cooling headers 25a, 26a, and 26c each time rolling is performed. This recording means can record data of changes over time in the flow rate Q and rolling speed V during rolling. Although details will be described later, the flow rate Q per unit time of the refrigerant for cooling the joint portion 4 and the rolling speed V affect the amount of bending of the joint portion 4, that is, the amount of bending of the end portion of the cut surface. Therefore, by recording the results of these Q and V, by investigating the relationship between the obtained Q and V and the bending amount of the joint part 4 actually obtained, the optimum flow rate Q and rolling The speed V can be obtained.

Next, the background to the present invention will be described. First, regarding the hat-shaped steel sheet pile 1 of the present invention, the residual stress difference Δσ (= σg−σf) between the maximum value σg of the residual stress of the joint portion 4 or the arm portion 5 and the minimum value σf of the residual stress of the flange portion 3 is calculated. The reason for the identification will be explained.
The present inventors conducted various investigations and examinations on the temperature distribution at the end of rolling, the residual stress distribution in the product, and the deformation of the end of the hat-shaped steel sheet pile 1 that was hot-rolled and straightened under various conditions. Went.

  FIG. 5 shows the measurement of the temperature profile in the full width direction of the hat-shaped steel sheet pile 1 at the entry side of the hot-cutting device 14 when the hat-shaped steel sheet pile 1 after finish rolling is cut by the hot-cutting device 14. This is an example. The temperature profile of two rolling materials is shown, and a thick line is a case where the joint part on the left side was experimentally cooled using water as a coolant in the joint part cooling device 25 described above. As in this example, in the hat-shaped steel sheet pile 1, the left and right joint portions 4 and the web portion 2 are finished at a higher temperature than the flange portion 3 and the arm portion 5. Moreover, it turns out that the temperature of the joint part 4 can be finished to low temperature by cooling the joint part 4 rather than the case where the joint part 4 is not cooled.

  FIG. 6 shows the result of measuring the residual stress in the longitudinal direction after cold-rolling the hat-shaped steel sheet pile 1 produced from the two materials shown in FIG. 5 over the width direction. Even after roller straightening, there is residual stress, which is tensile residual stress near the center in the width direction of the web portion 2 and the joint portion 4, and compressive residual stress near the flange portion 3. The product in which the joint portion 4 is cooled by finish rolling indicated by ◯ has a smaller difference in residual stress in the vicinity of the joint portion 4 and the flange portion 3 than the product without cooling of the joint portion 4 indicated by Δ. I understand that

  When the bending amount of the joint part 4 was investigated for these two products, the product without water cooling of the joint part 4 was +6.7 mm at the left joint part 4 and +6.1 mm at the right joint part 4. The product subjected to water cooling of the part 4 is +3.7 mm at the left joint part 4 and +4.9 mm at the right joint part 4, and the deformation of the joint part 4 is reduced by water cooling of the joint part 4 in finish rolling. It was recognized that As shown in FIG. 12, the bending amount of the joint portion 4 extends the joint outer edge line of the long regular portion, and the difference in the position in the width direction between the extended line and the outer end of the joint portion 4 at the long end portion. In the case where the end is widened, the sign is +, and the case where the end is narrow is the sign-.

  Next, in order to evaluate the above findings more quantitatively, the maximum residual stress value σg in the vicinity of the joint portion 4 and the minimum residual stress value σf in the vicinity of the flange portion 3 shown in FIG. The difference σg−σf was set as the residual stress difference Δσ, and the quantitative relationship with the bending amount of the joint portion 4 in various products was investigated. The results of this investigation are shown in FIG. In Fig. 7, among the hat-shaped steel sheet piles 1 with an effective width of 900 mm, the 10H size with a web thickness of 10.8 mm and an effective height of 230 mm is indicated by ◯, and the 25H size with a web thickness of 13.2 mm and an effective height of 300 mm is indicated by Δ. ing. Residual stress is measured by attaching a number of strain gauges in the full width direction on the front and back surfaces of the hat-shaped steel sheet pile in the longitudinal direction, measuring these initial strains, and then immediately adjacent to the strain gauge application position. The hat-shaped steel sheet pile was cold-cut in the width direction, and the strain after the residual stress was released by cold sawing was measured with these strain gauges. From the amount of strain change from the initial strain, The stress is calculated.

  From FIG. 7, it can be seen that the bending amount of the joint portion 4 can be arranged by the residual stress difference Δσ. When using the hat-shaped steel sheet pile 1, since the left and right joint parts 4 are fitted as shown in FIG. 11 (c), the bending amount of the joint part 4 has a tolerance for fitting, In the case of the hat-shaped steel sheet pile 1, it is necessary to be within about ± 4 mm. The range of the residual stress difference Δσ that satisfies the bending amount of the joint portion 4 within about ± 4 mm is 0 to 60 MPa in both cases of 10H and 25H.

  That is, the residual stress difference Δσ (= σg−σf), which is the difference between the maximum residual stress σg of the joint portion 4 and the minimum residual stress σf of the flange portion 3, is set within a range of 0 MPa to 60 MPa. The bending amount of the joint portion 4 can be set to such a level that there is no problem in fitting. In addition, when the joint part 4 is locally cooled and the temperature of the joint part 4 falls below the temperature of the arm part 5, the maximum value of the residual stress of the arm part 5 is larger than the maximum value of the residual stress of the joint part 4. Can become large. In this case, even if the difference between the maximum residual stress σg of the joint 4 and the minimum residual stress σf of the flange 3 is 60 MPa or less, the maximum residual compressive stress of the arm 5 and the residual of the flange 3 When the minimum value σf of the compressive stress exceeds 60 MPa, the bending amount of the joint portion 4 does not become within about ± 4 mm. Therefore, in the hat-shaped steel sheet pile 1 of the present invention, the residual stress difference Δσ (= σg−σf) between the residual stress maximum value σg of the joint portion 4 or the arm portion 5 and the residual stress minimum value σf of the flange portion 3 is 0 MPa or more. Must be 60MPa or less.

Next, a description will be given of the examination results that can suppress the bending amount of the joint portion 4 by cooling the joint portion 4 and have completed the manufacturing method of the hat-shaped steel sheet pile 1 of the present invention.
The difference between the maximum temperature Tg of the joint part 4 and the minimum temperature Tf of the flange part 3 shown in FIG. 5 is defined as a temperature difference ΔT (= Tg−Tf), and the relationship with the bending amount of the joint part 4 in the product is shown. investigated. In addition, the right and left joint portions 4 were used as individual data. The results of this investigation are shown in FIG. It can be seen from FIG. 8 that the amount of bending of the joint portion 4 can be organized even with the temperature difference ΔT. In the case of this data, the range of the temperature difference ΔT that satisfies the bending amount of the joint portion 4 within about ± 4 mm is 30 to 50 ° C.

  As described above, the reason why the bending amount of the joint portion 4 can be arranged by both the residual stress difference Δσ and the temperature difference ΔT is that ΔT and Δσ have a substantially linear correlation as shown in FIG. is there. Accordingly, the relationship between the temperature difference ΔT and the amount of bending at the end of the cut surface after cutting is determined, and finish rolling is performed so that a range of ΔT that allows the bending amount to be within an allowable value based on this relationship is obtained. Sometimes, the amount of bending of the joint portion 4 can be suppressed by cooling the joint portion 4. Alternatively, a relationship between the temperature difference ΔT and Δσ is determined, and rolling in the final hole shape K1 of the finish rolling mill 13 is performed so that a range of ΔT in which the residual stress difference Δσ is 0 MPa or more and 60 MPa or less is obtained based on this relationship. The amount of bending of the joint portion 4 can also be suppressed by cooling the joint portion 4.

  The temperature difference ΔT is the same time after the hot rolling is completed, that is, after the rolling in the final hole mold K1 of the finish rolling mill 13 is finished and until the temperature of the web portion 2 drops to 500 ° C. The difference between the minimum temperature Tf of the flange portion 3 and the maximum temperature Tg of the joint portion 4 or the arm portion 5 is taken. The difference in temperature ΔT between the minimum temperature Tf of the flange 3 and the maximum temperature Tg of the joint 4 or the arm 5 is only the difference between the maximum temperature of the joint 4 and the minimum temperature Tf of the flange 3. This is because even if the bending can be suppressed, the bending cannot be suppressed when the difference between the maximum temperature of the arm portion 5 and the minimum temperature Tf of the flange portion 3 is a range where the bending cannot be suppressed. Further, the temperature difference ΔT is the temperature difference at the same time after the hot rolling is completed, that is, after the rolling in the final die K1 of the finish rolling mill 13 is finished and until the temperature of the web part 2 drops to 500 ° C. The reason is that, after the temperature of the hat-shaped steel sheet pile 1 is lowered to a certain level, specifically, at the stage after the temperature of the web portion 2 is lowered to less than 500 ° C., bending is already generated. This is because a residual stress difference is generated. In other words, the residual stress difference Δσ cannot be changed unless the temperature difference ΔT at the stage of the web portion 2 at a temperature of 500 ° C. or higher is adjusted, and this does not contribute to curbing.

  Further, from the result shown in FIG. 5, the temperature difference ΔT decreases as the cooling of the joint portion 4 is increased. Therefore, if the flow rate Q of the cooling water supplied to the joint portion cooling header 25a per unit time is increased to some extent, the temperature difference ΔT is reduced. However, as described above, the cooling capacity of the joint portion 4 varies depending on the rolling speed V even at the same flow rate Q. Therefore, the cooling water flow rate Q may be changed according to the rolling speed V. Specifically, it was found that ΔT can be arranged by Q / V obtained by dividing the flow rate Q of the cooling water by the rolling speed V. Therefore, it is preferable to obtain the relationship between Q / V and ΔT in advance and adjust ΔT by changing Q / V. If there is no change in the rolling speed V, or even if the influence on ΔT is not so great when the flow rate Q is the same, ΔT is adjusted by changing only the flow rate Q without considering the rolling speed V. You may do it.

  In the case of the method of adjusting the temperature difference ΔT, the temperature profile in the full width direction of the hat-shaped steel sheet pile 1 after finish rolling is measured using the thermometer 31 described above, and the target at the finish rolling of the next material is determined from the measurement result. The flow rate Q of the refrigerant can be corrected so that ΔT can be achieved. By doing in this way, whenever the number of rolling is piled up, the control precision of temperature difference (DELTA) T improves and the amount of bending can be suppressed more.

  Next, an embodiment of a method for manufacturing the hat-shaped steel sheet pile 1 of the present invention, which can put the deformation suppression of the joint portion 4 into practical use by a simple method based on the above knowledge, will be described. Using the equipment shown in FIGS. 3 and 4, various cooling conditions were applied by finish rolling, and the bending amount of the joint portion 4 of each product obtained was investigated. An example of the survey results is shown in Fig. 10. The amount of bending of the joint part 4 can be arranged by Q / V using water as a refrigerant and dividing the cooling water flow rate Q (liter / second) of the joint part 4 by the finish rolling speed V (m / second) in the K1 hole type. There was found.

  As described above, the rolling speed is adjusted so as to be faster than the steady portion when the rolling is caught, and whether or not the product is bent during the rolling or the occurrence of wrinkles such as seizure. Therefore, the relationship between the value Q / V obtained by dividing the flow rate Q per unit time of the cooling water by the finish rolling speed V and the bending amount of the joint portion 4 at the end of the cut surface is determined. The Q / V range in which the bending amount is within an allowable range is set, and the cooling water flow rate Q is adjusted so that the Q / V falls within a certain value range in accordance with the change in the rolling speed V. The amount of deformation can be kept within tolerance.

  The flow rates of the refrigerant (cooling water in the present embodiment) on the surfaces of the left joint portion 4, the right joint portion 4, and the web portion 2 can be set individually. Since the joint shape of the hat-shaped steel sheet pile 1 is an asymmetric shape on the left and right as shown in FIG. 11B, a temperature difference is likely to occur between the left and right joint parts 4, but the cooling water flow rate of the left and right joint parts 4 By setting each individually, it is possible to cope with a case where deformation of only one joint portion 4 becomes a problem. The cooling of the surface of the web portion 2 is necessary when it is necessary to prevent warping during natural cooling on the CB (cooling bed) after rolling as described above. Therefore, the flow rate of the refrigerant on the surface of the web part 2 can be set independently of the flow rate of the refrigerant in the joint part 4, thereby having a relationship with the coolant flow rate in the joint part 4 for suppressing the bending of the joint part 4. However, it can be set depending on whether or not warpage occurs.

  The cooling of the surface of the web portion 2 is effective when the product length is as long as, for example, 15 m or longer. FIG. 13 is a schematic diagram showing a state in which an upward warp is generated in the hat-shaped steel sheet pile 1. As shown in FIG. 13, when a straight line connecting the upper surfaces of the webs 2 at both ends in the longitudinal direction of the hat-shaped steel sheet pile 1 having a certain product length is used as a reference straight line, a perpendicular is dropped from the reference straight line to the upper surface of the web 2 in the longitudinal center. The distance between the reference straight line on the perpendicular and the upper surface of the web 2 is defined as the warp amount S at the product length. Since the warpage amount S increases almost in proportion to the square of the product length, even when manufactured under the same manufacturing conditions, the warpage amount on the CB (cooling bed) of the hat-shaped steel sheet pile 1 having a product length of 20 m is: The length of the hat-shaped steel sheet pile 1 having a product length of 10 m is very large, approximately four times the amount of warpage on the CB (cooling bed).

When manufacturing the hat-shaped steel sheet pile 25H having a product length of 20 m using the equipment shown in FIGS. 3 and 4, it is obtained by applying various web part cooling conditions using water as a refrigerant in finish rolling. The amount of warpage S of each product was investigated. As a result, as shown in FIG. 14, the warp amount S is calculated by Qw / V obtained by dividing the cooling water flow rate Qw (liter / second) to the web portion 2 by the finish rolling speed V (m / second) in the K1 hole mold. It turns out that it can be organized. From this relationship, it is possible to set a range or condition of Qw / V in which the warp amount S is within an allowable range.
In all of the embodiments described above, water is used as the refrigerant, but other refrigerants can also be used.

  In addition, when the hat-shaped steel sheet pile 1 after rolling is naturally cooled to room temperature by CB (cooling floor), the bending of the joint part 4 is confirmed, and the bending amount of the joint part 4 is too large (when exceeding +4 mm). The bending amount of the joint portion 4 can be controlled by a method of increasing the cooling water flow rate for the subsequent rolled material, slowing the rolling speed, or performing both of them. Conversely, when the amount of bending of the joint portion 4 is too small (= contracted inward), it is possible to perform control such as reducing the coolant flow rate of the joint portion 4 or increasing the rolling speed.

<Effect of embodiment>
(1) A hat-shaped steel sheet pile 1 according to an aspect of the present invention is a hat-shaped steel sheet pile 1 including a web portion 2, a flange portion 3, an arm portion 5, and a joint portion 4, and includes a joint portion 4 or an arm portion. The residual stress difference Δσ (= σg−σf), which is the difference between the maximum residual stress σg of No. 5 and the minimum residual stress σf of the flange portion 3, is 0 MPa or more and 60 MPa or less.
According to the configuration of (1) above, the amount of bending of the cut surface end after cutting the hat-shaped steel sheet pile 1 along the width direction can be set to a level that does not cause a problem in fitting.

(2) The manufacturing method of the hat-shaped steel sheet pile 1 which concerns on 1 aspect of this invention is the hot-rolling of the hat-shaped steel sheet pile 1 comprised from the web part 2, the flange part 3, the arm part 5, and the joint part 4. In the manufacturing method of the hat-shaped steel sheet pile 1 that is shaped into the shape of the hat-shaped steel sheet pile 1 and then cut in the width direction, after the hot rolling is finished, until the temperature of the web portion 2 drops to 500 ° C. The difference between the lowest temperature Tf of the flange portion 3 and the highest temperature Tg of the joint portion 4 or the arm portion 5 at the same time is defined as a temperature difference ΔT (= Tg−Tf), and the temperature difference ΔT and the cutting are performed. Then, a relationship with the bending amount of the end portion of the cut surface is determined, and based on this relationship, a range of ΔT that allows the bending amount to be within an allowable value is obtained. The joint part 4 is cooled during rolling. To.
According to the configuration of the above (2), the hat-shaped steel sheet pile 1 in which the bending amount of the cut end portion after cutting the hat-shaped steel sheet pile 1 along the width direction is such that there is no problem in joint fitting. Can be manufactured.

(3) The manufacturing method of the hat-shaped steel sheet pile 1 which concerns on 1 aspect of this invention is the hot-rolling of the hat-shaped steel sheet pile 1 comprised from the web part 2, the flange part 3, the arm part 5, and the joint part 4. In the manufacturing method of the hat-shaped steel sheet pile 1 that is shaped into the shape of the hat-shaped steel sheet pile 1 and then cut in the width direction, after the hot rolling is finished, until the temperature of the web portion 2 drops to 500 ° C. The difference between the minimum temperature Tf of the flange portion 3 and the maximum temperature Tg of the joint portion 4 or the arm portion 5 at the same time is the temperature difference ΔT (= Tg−Tf), and the residual of the joint portion 4 or the arm portion 5 The difference between the stress maximum value σg and the residual stress minimum value σf of the flange portion 3 is defined as a residual stress difference Δσ (= σg−σf), and the relationship between the temperature difference ΔT and the residual stress difference Δσ is determined. Based on this, the residual stress difference Δσ can be set to 0 MPa or more and 60 MPa or less. And performing cooling of the joint portion 4 in the rolling of the final grooved K1 mill 13 finish so obtained.
According to the configuration of (3) above, the hat-shaped steel sheet pile 1 in which the amount of bending at the end of the cut surface after cutting the hat-shaped steel sheet pile 1 along the width direction is such that there is no problem in joint fitting. Can be manufactured.

(4) The manufacturing method of the hat-shaped steel sheet pile according to one aspect of the present invention includes the hot-rolling of the hat-shaped steel sheet pile 1 including the web part 2, the flange part 3, the arm part 5, and the joint part 4 by hot rolling. In the manufacturing method of the hat-shaped steel sheet pile 1 that is shaped into the shape of the hat-shaped steel sheet pile 1 and then cut in the width direction, the joint portion 4 is cooled in the rolling with the final hole mold K1 of the finish rolling mill 13, and the cooling The relationship between the value Q / V obtained by dividing the flow rate Q per unit time of the refrigerant to be divided by the rolling speed V at the time of rolling by the finish rolling mill 13 and the amount of bending at the end of the cut surface after the cutting is previously set. A range of the value Q / V in which the bending amount is within an allowable range is set based on the relationship, and the value Q / V is set in the set range corresponding to the change in the rolling speed V. To adjust the flow rate Q of the refrigerant per unit time. The features.
According to the configuration of (4) above, the hat-shaped steel sheet pile 1 in which the amount of bending at the end of the cut surface after cutting the hat-shaped steel sheet pile 1 along the width direction is such that there is no problem in joint fitting. Can be manufactured.

(5) In the configuration of any one of (2) to (4), the joint portion 4 is cooled separately for the left and right joint portions 4.
Since the joint shape of the hat-shaped steel sheet pile 1 is asymmetrical on the left and right sides, a temperature difference is likely to occur between the left and right joint parts 4, but according to the configuration of (5) above, the left and right joint parts 4 are cooled. By individually setting, it is possible to cope with the case where deformation of only one joint portion 4 becomes a problem.

(6) In the configuration of any one of (2) to (5), the web portion 2 is cooled in addition to the cooling of the joint portion 4.
According to the configuration of (6) above, when the hat-shaped steel sheet pile 1 is naturally cooled on the CB (cooling bed) after rolling, the hat-shaped steel sheet pile 1 can be prevented from being warped.

(7) The manufacturing equipment for a hat-shaped steel sheet pile according to an aspect of the present invention includes a hat-shaped steel sheet pile 1 including a web portion 2, a flange portion 3, an arm portion 5 and a joint portion 4 by hot rolling. A hot rolling mill (rough rolling mill 11, intermediate rolling mill 12, and finish rolling mill 13) shaped into the shape of the hat-shaped steel sheet pile 1 and the hat-shaped steel sheet pile 1 obtained by the hot rolling in the width direction In a production facility for a hat-shaped steel sheet pile 1 having a sawing device (hot sawing device 14) for cutting, the joint portion 4 is placed in a guide (front guide 23) of a finish rolling mill 13 of the hot rolling mill. A joint part cooling device 25 for cooling is provided, the joint part cooling device 25 can adjust the flow rate Q per unit time of the refrigerant that cools the joint part 4, and the finish rolling mill 13 can adjust the rolling speed V. And records the results of the flow rate Q and rolling speed V It characterized by having a recording means that.
According to the configuration of the above (7), the flow rate Q of the refrigerant that cools the joint portion 4 that affects the bending amount of the end portion of the cut surface after the hat-shaped steel sheet pile 1 is cut along the width direction, and finish rolling. Since the rolling speed V of the machine 13 can be adjusted and the results of the flow rate Q and the rolling speed V can be recorded, it is optimal from the relationship between the amount of bending at the end of the cut surface, the flow rate Q, and the rolling speed V with a sawing device. It is possible to find a suitable rolling speed and flow rate Q.

(8) In the configuration of (7) above, the minimum temperature Tf of the flange portion 3 and the joint portion at the same time after the hot rolling is finished and until the temperature of the web portion 2 drops to 500 ° C. 4 to the maximum temperature Tg of the arm part 5 per unit time of the refrigerant from the joint part cooling device 25 so that the temperature difference ΔT (= Tg−Tf) is within a preset allowable value. The flow rate control means for setting the flow rate Q is provided.
According to the configuration of (8) above, the hat-shaped steel sheet pile 1 in which the amount of bending at the end of the cut surface after cutting the hat-shaped steel sheet pile 1 along the width direction is such that there is no problem in joint fitting. Can be manufactured.

(9) In the configuration of (8) above, the temperature in the full width direction of the hat-shaped steel sheet pile 1 on the downstream side of the finish rolling mill 13 and upstream of the position where the temperature of the web portion 2 drops to 500 ° C. It has a thermometer 31 for measuring the distribution, and the flow rate control means corrects the flow rate Q of the refrigerant during finish rolling of the next material based on the temperature distribution measurement result by the thermometer 31.
According to the configuration of (9) above, the control accuracy of ΔT is improved every time the number of rolled sheets is increased, and the hat-shaped steel sheet pile 1 having a degree of no problem in fitting can be manufactured.

(10) In the configuration of (7) above, the amount of bending is allowed based on the relationship between the value Q / V obtained by dividing the flow rate Q by the rolling speed V and the amount of bending of the cut end portion after cutting. A range of the value Q / V that falls within the range is set in advance, and the flow rate Q of the refrigerant per unit time is set so that the value Q / V falls within the set range corresponding to the change in the rolling speed V. It has the flow control means to adjust, It is characterized by the above-mentioned.
According to the configuration of (10) above, the hat-shaped steel sheet pile 1 in which the amount of bending at the end of the cut surface after cutting the hat-shaped steel sheet pile 1 along the width direction is such that there is no problem with fitting fitting. Can be manufactured.

(11) In the configurations of (7) to (10), the guide (front guide 23) has a web part cooling device 26 for cooling the web part 2 in addition to the joint part cooling device 25. Features.
According to the configuration of (11) above, it is possible to manufacture the hat-shaped steel sheet pile 1 that suppresses the occurrence of warping when the hat-shaped steel sheet pile 1 is naturally cooled on the CB (cooling bed) after rolling.

<Example 1>
A hat-shaped steel sheet pile 10H having a web thickness of 10.8 mm and an effective width of 900 mm was manufactured on the hat-shaped steel sheet pile rolling production line shown in FIGS.
A thermometer 31 is arranged in front of a hot sawing device (hot saw) 14, and the temperature distribution in the width direction of the hat-shaped steel sheet pile 1 after finish rolling is measured with this thermometer 31. The target of the difference ΔT between the maximum temperature of 4 and the minimum temperature of the flange portion 3 was set from the relationship between the temperature difference ΔT and the bending amount of the joint portion 4. Specifically, from the relationship between the temperature difference ΔT shown in FIG. 8 and the bending amount of the joint portion 4, the target value of 40 ° C. and the target range of 30 to 50 are set as a range of ΔT that allows the bending amount to be within an allowable value (± 4 mm). The joint part cooling water flow rate was individually adjusted on the left and right sides during finish rolling in the K1 hole mold. On the other hand, in the comparative example, the case (comparative example 1) which does not implement joint part cooling at all and the case (comparative example 2) which cools by a maximum flow rate were implemented. Since the temperature profile changes from time to time with the time of cutting with the hot sawing device 14, the temperature difference ΔT was calculated from the temperature profile when the maximum temperature of the web part 2 was 550 ° C. In all cases, the finish rolling speed is 2 m / s.

  The hat-shaped steel sheet pile 1 manufactured in this way is naturally cooled to room temperature in the cooling bed CB, then leveler-corrected, and then subjected to cold sawing at the longitudinal center of the product. The amount of deformation was investigated and the residual stress was also investigated. The results are summarized in Table 1.

  From the results of Table 1, the target of the difference ΔT between the maximum temperature of the joint part 4 and the minimum temperature of the flange part 3 is set from the relationship between the temperature difference ΔT and the bending amount of the joint part, and the temperature difference ΔT follows this target. Thus, in the fitting example in which the joint portion 4 is cooled, the bending amount of the joint portion 4 is within ± 4 mm for both the left and right joint portions 4. On the other hand, in Comparative Example 1 and Comparative Example 2, since the cooling water flow rate of the joint part 4 was inappropriate, the bending amount of the joint part 4 was not satisfied within ± 4 mm.

<Example 2>
Next, the hat-shaped steel sheet pile 25H having a web thickness of 13.2 mm and an effective width of 900 mm is manufactured on the rolling production line of the hat-shaped steel sheet pile 1 shown in FIGS. 1, 2, 3, and 4. did. In the present example, 5 rolling materials are prepared for each of the conforming example and the comparative example, and the rolling speed in rolling with the K1 hole die which is the final final rolling is changed between 1.0 to 4.0 m / s for each rolling material. I went. The value obtained by dividing the joint cooling water flow rate Q by the rolling speed V (Q / V) is a target value 2.0 (L / s) / (m / s) from FIG. 10 and an allowable range of 1.6 to 2.4. Rolling was carried out when the flow rate of the cooling water was adjusted (conforming example) and when the flow rate of the cooling water was kept constant regardless of the change in the finishing rolling speed (comparative example).
About these products, the amount of bending of the joint at the end of the hot-cut product was investigated. The results are shown in Table 2.

  From the results in Table 2, the target value of Q / V is set to 2.0 so that the bending amount of the joint portion 4 can be within ± 4 mm from the relationship between the Q / V value and the bending amount of the joint portion 4 shown in FIG. In the conforming example in which the allowable range is 1.6 to 2.4 and the cooling water flow rate of the joint portion 4 is adjusted, the bending amount of the joint portion 4 may be within ± 4 mm in any finish rolling speed condition. Recognize. On the other hand, in the comparative example in which the cooling water flow rate of the joint portion 4 is constant regardless of the finish rolling speed V, depending on the finish rolling speed condition, the bending amount of the joint portion 4 may be within ± 4 mm (V = In the case of 2.0 m / s), it can be seen that the bending amount of the joint portion 4 may not be within ± 4 mm due to a change in the finish rolling speed.

<Example 3>
In the rolling production line for the hat-shaped steel sheet pile 1 shown in FIGS. 1, 2, 3, and 4, the product length is 20 m among the hat-shaped steel sheet pile 25H having a web thickness of 13.2 mm and an effective width of 900 mm. The production of the long product was implemented. In production, the rolling speed in rolling with the K1 hole mold, which is the final finishing rolling, is 2.0 m / s, and the value obtained by dividing the joint cooling water amount Q by the rolling speed V (Q / V) is 2.0 (L / s). ) / (M / s). And 3 each was manufactured about the case where web cooling was performed by making web cooling water quantity Qw 4.0 (L / s), and the case where web cooling was not performed.

  As a result, the bending amount of the joint portion 4 was within ± 4 mm for all three products manufactured by performing web cooling and three products manufactured without performing web cooling. On the other hand, when the web cooling was performed, the warpage amount on the CB was 50 mm or less for all three products, and there was no particular problem. However, when the web cooling was not performed, the warpage amount for all three products was the same. S became as large as 200 mm or more, skewing of the product occurred in the product conveyance by CB, and contact and overlap with adjacent products occurred. For this reason, for the products that were not cooled by the web, the operator used an overhead crane to correct the conveyance state on the CB, and the production pitch was reduced during that time.

DESCRIPTION OF SYMBOLS 1 Hat-shaped steel sheet pile 2 Web part 3 Flange part 4 Joint part 5 Arm part 10 Heating furnace 11 Rough rolling mill (hot rolling mill)
12 Intermediate rolling mill (hot rolling mill)
13 Finishing mill (hot rolling mill)
13a mill motor 14 hot sawing device (saw cutting device: hot saw HS)
21 Upper rolling roll 22 Lower rolling roll 23 Front guide (guide)
23a Upper Guide 23b Lower Guide 24 Rear Guide 25 Joint Cooling Device 25a Joint Cooling Header 25b Joint Cooling Nozzle 25e Flow Control Valve (Joint Cooling Water Flow Control Valve)
26 web part cooling device 26a web upper surface cooling header 26b web upper surface cooling nozzle 26c web lower surface cooling header 26d web lower surface cooling nozzle 26e flow rate adjusting valve (web upper surface cooling water flow rate adjusting valve)
29 Cooling water pump 30 Arithmetic unit (flow rate control means)
31 Thermometer

Claims (11)

A hat-shaped steel sheet pile composed of a web part, a flange part, an arm part and a joint part,
The residual stress difference Δσ (= σg−σf), which is the difference between the residual stress maximum value σg of the joint part or the arm part and the residual stress minimum value σf of the flange part, is 0 MPa or more and 60 MPa or less. Hat-shaped steel sheet pile. In a manufacturing method of a hat-shaped steel sheet pile, in which a hat-shaped steel sheet pile composed of a web part, a flange part, an arm part, and a joint part is shaped into the shape of the hat-shaped steel sheet pile by hot rolling and then cut in the width direction. ,
The difference between the minimum temperature Tf of the flange part and the maximum temperature Tg of the joint part or the arm part at the same point in time until the temperature of the web part drops to 500 ° C. after finishing the hot rolling A difference ΔT (= Tg−Tf) is set, and a relationship between the temperature difference ΔT and the amount of bending at the end of the cut surface after the cutting is determined, and ΔT that allows the bending amount to be within an allowable value based on this relationship. The hat-shaped steel sheet pile manufacturing method is characterized in that the joint portion is cooled in rolling in a final hole mold of a finish rolling mill so as to obtain a range of the above. In a manufacturing method of a hat-shaped steel sheet pile, in which a hat-shaped steel sheet pile composed of a web part, a flange part, an arm part, and a joint part is shaped into the shape of the hat-shaped steel sheet pile by hot rolling and then cut in the width direction. ,
The difference between the minimum temperature Tf of the flange part and the maximum temperature Tg of the joint part or the arm part at the same point in time until the temperature of the web part drops to 500 ° C. after finishing the hot rolling The difference ΔT (= Tg−Tf), the difference between the residual stress maximum value σg of the joint portion or the arm portion and the residual stress minimum value σf of the flange portion is defined as a residual stress difference Δσ (= σg−σf), and the temperature The relationship between the difference ΔT and the residual stress difference Δσ is determined. Based on this relationship, rolling in the final hole shape of the finish rolling mill so as to obtain a range of ΔT that allows the residual stress difference Δσ to be 0 MPa or more and 60 MPa or less. The method of manufacturing a hat-shaped steel sheet pile, wherein the joint portion is cooled in the process. In a manufacturing method of a hat-shaped steel sheet pile, in which a hat-shaped steel sheet pile composed of a web part, a flange part, an arm part, and a joint part is shaped into the shape of the hat-shaped steel sheet pile by hot rolling and then cut in the width direction. ,
Cooling the joint in rolling in the final hole mold of the finish rolling mill,
The relationship between the value Q / V obtained by dividing the flow rate Q per unit time of the refrigerant for cooling by the rolling speed V at the time of rolling by the finish rolling mill and the amount of bending at the end of the cut surface after the cutting. Based on the relationship, the range of the value Q / V in which the bending amount is within an allowable range is set based on the relationship, and the value Q / V is set in the set range corresponding to the change in the rolling speed V. As described above, the flow rate Q per unit time of the refrigerant is adjusted as described above.   The method for manufacturing a hat-shaped steel sheet pile according to any one of claims 2 to 4, wherein the joint portion is cooled separately for the left and right joint portions.   The method for manufacturing a hat-shaped steel sheet pile according to any one of claims 2 to 5, wherein the web portion is cooled in addition to the cooling of the joint portion. A hot rolling mill that forms a hat-shaped steel sheet pile composed of a web portion, a flange portion, an arm portion, and a joint portion into the shape of the hat-shaped steel sheet pile by hot rolling, and a hat obtained by the hot rolling In a production facility for a hat-shaped steel sheet pile having a sawing device for cutting the shape steel sheet pile in the width direction,
A joint part cooling device for cooling the joint part in a guide of a finish rolling mill of the hot rolling mill,
The joint part cooling device can adjust the flow rate Q per unit time of the refrigerant that cools the joint part,
The finish rolling mill can adjust the rolling speed V,
A production facility for a hat-shaped steel sheet pile, comprising recording means for recording the results of the flow rate Q and the rolling speed V.   It is the difference between the lowest temperature Tf of the flange part and the highest temperature Tg of the joint part or the arm part at the same time until the temperature of the web part drops to 500 ° C. after finishing the hot rolling. It is characterized by comprising a flow rate control means for setting the flow rate Q per unit time of the refrigerant from the joint part cooling device so that the temperature difference ΔT (= Tg−Tf) is within a preset allowable value. The manufacturing equipment of the hat-shaped steel sheet pile according to claim 7. On the downstream side of the finish rolling mill, on the upstream side from the position where the temperature of the web part drops to 500 ° C., a thermometer that measures the temperature distribution in the full width direction of the hat-shaped steel sheet pile,
The said flow control means correct | amends the flow volume Q of the said refrigerant | coolant at the time of finish rolling of the next material based on the temperature distribution measurement result by this thermometer, The manufacturing equipment of the hat-shaped steel sheet pile of Claim 8 characterized by the above-mentioned.   From the relationship between the value Q / V obtained by dividing the flow rate Q by the rolling speed V and the amount of bending at the end of the cut surface after the cutting, the range of the value Q / V in which the bending amount is within an allowable range. Is set in advance, and has flow rate control means for adjusting the flow rate Q per unit time of the refrigerant so that the value Q / V falls within the set range corresponding to the change in the rolling speed V. The manufacturing equipment of the hat-shaped steel sheet pile according to claim 7.   The equipment for producing a hat-shaped steel sheet pile according to any one of claims 7 to 10, further comprising a web part cooling device for cooling the web part in addition to the joint part cooling device in the guide.

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