JP6947268B2 - Manufacturing method of hat-shaped steel sheet pile - Google Patents

Description

The present invention relates to a method for manufacturing a hat-shaped steel sheet pile, and more particularly to a method for manufacturing a hat-shaped steel sheet pile in which an end portion having excellent dimensional accuracy can be obtained after sawing.

Shaped steel manufactured by hot rolling is warped after cooling due to the difference in thickness of each part of the cross section and the temperature difference due to the difference in cooling conditions. End deformation occurs when the residual stress generated in the cross section is released at the hot sawn portion.
Patent Document 1 relates to a method for restraint cooling of a shaped steel, and in order to eliminate warpage caused by uneven temperature in a cross section that occurs during hot rolling, the shaped steel being cooled is based on the shape steel temperature at the start of restraint cooling. It is described that the temperature, the transformation point rate, etc. are estimated, and the restraint cooling conditions are selected based on these so that the warp does not occur.
If the shaped steel is deformed at the end, it is necessary to correct the shape of the end after sawing, but with leveler straightening, it is difficult to correct it because it is not possible to apply reduction to the end in the longitudinal direction. On the other hand, if press straightening is used, straightening is possible, but the production efficiency is lowered.

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. Due to the difference, the flange is cooled faster than the web, and the end in the longitudinal direction, which is prone to shape defects due to the release of thermal stress by sawing, has a specific range of surface temperature before finish rolling, and after sawing. It is stated that the dimensional tolerance is achieved by cooling the base of the flange (corner).
Patent Document 3 relates to a method for controlling the shape of an end portion of a shaped steel, in which the temperature of the outer surface of the flange or web closest to the hot saw is measured, and cooling without edge bending, which is obtained from the correlation record between the temperature and the edge bend. It is stated that forced cooling is performed during and / or after sawing to a reference temperature.

Japanese Unexamined Patent Publication No. 2-15816 Japanese Unexamined Patent Publication No. 53-81464 Japanese Unexamined Patent Publication No. 55-139105

By the way, as shown in FIG. 11A as a whole of the cross-sectional shape, the web portion 2, the flange portion 3, the joint portion 4, and the arm portion 5 are provided between the flange portion 3 and the joint portion 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 the arm portion 5 is provided. For this reason, in the hat-shaped steel sheet pile 1, the residual stress generated after cooling due to the non-uniformity of the temperature of each part in the cross section at the time of rolling finish has a large influence on the cross-sectional shape, and especially after rolling, it is sawn to the product length ( When the hat-shaped steel sheet pile 1 is sawn in the width direction), the deformation of the end portion due to the residual stress becomes larger, and in some cases, the dimensional tolerance may be deviated. FIG. 11B shows an enlarged state of the joint portion 4 of the hat-shaped steel sheet pile 1, and FIG. 11C shows a state in which the joint portions 4 of the hat-shaped steel sheet pile 1 are fitted to each other. ..

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

The technique described in Patent Document 1 is a technique for preventing the steel sheet pile from warping in the vertical direction, and does not prevent the trumpet deformation at the end of the product. In addition, a very large capital investment is required to perform restraint cooling.
The technique described in Patent Document 2 is a technique for cooling the flange base portion of the U-shaped steel sheet pile during hot sawing after rolling, and is not a technique that can be directly applied to the hat-shaped steel sheet pile. In particular, since the hat-shaped steel sheet pile has a more complicated shape and a larger size (total width dimension) than the U-shaped steel sheet pile, the number of rolling passes increases and the temperature during hot sawing becomes extremely low. Therefore, this technology cannot be expected to be effective. In addition to hot sawing, steel sheet piles are often coldly sawed to a predetermined length, but this technique cannot handle cold sawed steel sheet piles at all.

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

Therefore, the present invention has been made in view of such a problem, and "trumpet deformation" is applied to the end portion of a hat-shaped steel sheet pile cut to a predetermined product length regardless of whether it is hot or cold after rolling. It is an object of the present invention to provide a method for manufacturing a hat-shaped steel sheet pile that can realize a well-shaped hat-shaped steel sheet pile at low cost without a shape defect such as "reverse trumpet deformation".

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 formed into the shape of the hat-shaped steel sheet pile by hot rolling and then cut in the width direction. In the method for manufacturing a hat-shaped steel sheet pile, the minimum temperature Tf of the flange portion and the joint portion or the arm at the same time point between the completion of the hot rolling and the temperature drop of the web portion to 500 ° C. The difference from the maximum temperature Tg of the part is defined as the temperature difference ΔT (= Tg−Tf), and the relationship between the temperature difference ΔT and the bending amount of the end of the cut surface after the cutting is determined, and based on this relationship. Provided is a method for manufacturing a hat-shaped steel sheet pile, which comprises cooling the joint portion in rolling in the final hole type of a finishing rolling mill so that a range of ΔT capable of keeping the bending amount within an allowable value can be obtained. NS.

According to the method for manufacturing a hat-shaped steel sheet pile according to the present invention, a hat-shaped steel sheet pile that can inexpensively realize a hat-shaped steel sheet pile that can suppress deformation of the longitudinal end portion when sawed hot or cold is manufactured. The method is provided.

It is a top view which showed the manufacturing line of the hat-shaped steel sheet pile which manufactures the hat-shaped steel sheet pile which concerns on one Embodiment of this invention. It is a front view which shows the hole shape of a finishing rolling mill. It is a figure which shows the front guide, the joint part cooling device and the web part cooling device installed in the front surface of the K1 hole type, (a) shows the front view, and (b) shows the 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 in the full width direction of a hat-shaped steel sheet pile after finish rolling. It is a graph which shows an example of the width direction distribution of the longitudinal residual stress of a hat-shaped steel sheet pile. It is a graph which shows the relationship between the residual stress difference Δσ and the amount of deformation of an end part (the amount of bending of a joint part). It is a graph which shows the relationship between the temperature difference ΔT and the amount of deformation of an end part (the amount of bending of a joint part). It is a graph which shows the relationship between the temperature difference ΔT and the residual stress difference Δσ. It is a graph which shows the relationship between Q / V and the amount of deformation of an end part (the amount of bending of a joint part). A hat-shaped steel sheet pile is shown, (a) is a view showing the entire cross-sectional shape of the hat-shaped steel sheet pile, (b) is a view showing an enlarged state of a joint portion of the hat-shaped steel sheet pile, and (c) is a hat. It is a figure which shows the state which the joint part of a shaped steel sheet pile is fitted with each other. It is a schematic diagram which shows the deformation of the end portion in the longitudinal direction of a hat-shaped steel sheet pile, (a) shows the trumpet deformation, and (b) shows the reverse trumpet deformation. It is a schematic diagram which shows the state which a hat-shaped steel sheet pile has a warp (upward warp). It is a graph which shows the relationship between the web cooling water amount Qw / rolling speed V, and the warpage amount S.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that each drawing is a schematic one and may differ from the actual one. In addition, the following embodiments exemplify devices and methods for embodying the technical idea of the present invention, and do not specify the configuration to the following. That is, the technical idea of the present invention can be modified in various ways 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 hat-shaped steel sheet pile production line 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 finishing rolling mill 13. Further, the hat-shaped steel sheet pile production line is provided with a hot saw cutting 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.
The slabs and blooms, which are the raw materials, are heated to a predetermined temperature in the heating furnace 10, and the rough rolling mill 11, the intermediate rolling mill 12, and the finishing rolling mill 13 are hot-hole-rolled in this order, and the hat-shaped rolling mill shown in FIG. 11 is formed. Finished in product shape. The hot saw cutting device 14 hot cuts a rolled product to a predetermined length.

A plurality of hole molds are engraved in each rolling mill. For example, in the finish rolling mill 13, as shown in FIG. 2, two hole molds K2 and K1 are engraved on the upper rolling roll 21 and the lower rolling roll 22. Has been done. The K1 hole type is a hole type for final rolling, and claw bending and forming rolling are performed at the same time. The finish rolling is a total of 3 passes of reverse rolling, and the K2 hole type rolling is the first pass of rolling from the front surface (left side in FIG. 1) to the rear surface (right side in FIG. 1) of the finish rolling mill 13. Is rolled. The K1 hole type rolling is performed by reverse rolling in the second pass, and is rolled from the rear surface to the front surface side of the finish rolling mill 13. The third pass of 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 mill 13 but not rolled.

FIG. 3 is a schematic view showing a front guide 23 installed on the front surface of the K1 hole type, and a joint portion cooling device 25 and a web portion cooling device 26 installed in the front guide 23. FIG. 3A is a front view seen from the rolling direction, and FIG. 3B is a side view. The front guide 23 has an upper guide 23a and a lower guide 23b that guide the web portion 2, the flange portion 3, and the arm portion 5 of the hat-shaped steel sheet pile. A joint portion cooling header 25a is arranged in the upper guide 23a, and the joint portion cooling nozzle 25b is provided in the joint portion cooling header 25a. The joint portion cooling header 25a extends in the rolling direction (the left-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, and the joint portion cooling header 25a is located. Multiple pieces are arranged along the extending direction of. Then, the joint portion cooling nozzle 25b can eject the refrigerant toward the joint portion 4, and the joint portion 4 of the hat-shaped steel sheet pile is cooled by the joint portion cooling nozzle 25b. The joint portion cooling header 25a, the joint portion cooling nozzle 25b, the joint portion cooling water flow rate adjusting valve 25e described later, and the arithmetic device 30 for adjusting the opening degree of the joint portion cooling water flow rate adjusting valve 25e constitute the joint portion cooling device 25. doing. In this figure, the joint portion cooling device 25 is arranged on the upper guide 23a to cool the joint portion 4 from above, but the joint portion cooling header 25a and the joint portion cooling nozzle 25b are arranged on the lower guide 23b from below. The joint portion 4 may be cooled. Further, the portion of the joint portion 4 to be cooled most is the protrusion 4a of the joint portion 4 (see FIG. 11B), but the protrusion 4a is centered on the claw portion 4b and the arm portion 5. Cooling may be performed. Further, the joint portion cooling device 25 may be provided on the rear surface guide 24 (see FIG. 4).

A web upper surface cooling header 26a and a web upper surface cooling nozzle 26b are also arranged on the upper guide 23a, and 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 arranged at a position facing the upper surface of the web portion 2 of the web upper surface cooling header 26a, and the refrigerant can be injected to the upper surface of the web portion 2. A web lower surface cooling header 26c and a web lower surface cooling nozzle 26d are arranged on the lower guide 23b to cool 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 arranged at a position facing the lower surface of the web portion 2 of the web lower surface cooling header 26c, and the refrigerant can be injected to 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-right direction in FIG. 3B) like the joint portion 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 extending direction of the header so that a predetermined cooling capacity can be exhibited. These, the web upper surface cooling header 26a, the web upper surface cooling nozzle 26b, the web lower surface cooling header 26c, and the web lower surface cooling nozzle 26d, the web upper surface cooling water flow rate adjusting valve 26e, the web lower surface cooling water flow rate adjusting valve 26f, and the web lower surface cooling water flow rate adjusting valve 26f, which will be described later. The web unit cooling device 26 is composed of a calculation device 30 that adjusts the opening degree of the web upper surface cooling water flow rate adjusting valve 26e and the web lower surface cooling water flow rate adjusting valve 26f. The web portion cooling device 26 may be provided on the rear surface guide 24.

FIG. 4 is a schematic view 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, the web upper surface cooling header 26a, and the web lower surface cooling header 26c (not shown in FIG. 4) provided on the upper guide 23a of the front guide 23 of the hole type K1 are cooling water pipes, respectively. Is connected to the cooling water pump 29. Each cooling water pipe has a flow rate adjusting valve 25e (joint part cooling water flow rate adjusting valve 25e), 26e (web upper surface cooling water flow rate adjusting valve 26e), and 26f (web lower surface cooling water flow rate adjusting valve 26f: not shown). The flow rate adjusting valves 25e, 26e, 26f are provided, and the amount of cooling water supplied to the cooling headers 25a, 26a, 26c, that is, the flow rate Q per unit time can be individually adjusted. The arithmetic unit 30 adjusts the opening degree of the flow rate adjusting valves 25e, 26e, 26f.

The arithmetic unit 30 adjusts the opening degrees of the flow rate adjusting valves 25e, 26e, and 26f, sends a signal of a rotation speed command to the mill motor 13a of the finishing rolling mill 13, and controls the rolling speed of the hat-shaped steel sheet pile 1 by the finishing 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 rolling speed V) of the finish rolling mill 13 based on the rolling condition information of the material to be rolled from a higher-level computer (not shown). A rotation speed command signal is sent to 13a. The rolling speed V (m / sec) is made faster than the stationary portion at the time of biting in rolling, and is adjusted based on the presence or absence of bending and the presence or absence of flaws such as seizure. The arithmetic unit 30 adjusts the opening degree of the flow rate adjusting valves 25e, 26e, 26f, and the unit time of the refrigerant (water in this embodiment) for cooling the upper surface of the joint portion 4, the upper surface of the web portion 2, and the lower surface of the web portion 2. It functions as a flow rate control means for adjusting the flow rate Q (liter / sec) per unit. When the rolling speed V changes, the flow rate Q per unit time of the refrigerant for exerting a constant amount of cooling capacity changes. Therefore, in the present embodiment, the arithmetic unit 30 changes each cooling header 25a according to the change in the rolling speed V. , 26a, 26c are adjusted so that the flow rate Q of the cooling water supplied per unit time is adjusted. Specifically, each flow rate adjusting valve 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 and 26f is adjusted to control the flow rate Q of the cooling water to each of the cooling headers 25a, 26a and 26c.

The specific numerical range of Q / V is the relationship between the Q / V value and the bending amount of the cut surface end after cutting with the hot saw cutting device 14 for the joint cooling device 25, or Q / 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 either relationship, it is set as a Q / V range in which the bending amount is within the allowable range, or a Q / V range in which the temperature difference ΔT is within a predetermined range. The details of the reason why the bending of the cut surface end can be suppressed by adjusting the flow rate Q of the cooling water from the joint cooling device 25 so that the Q / V is within a certain range will be described later.

Further, the reason why the web portion 2 is cooled by the web portion cooling device 26 is to prevent warpage during natural cooling on the CB (cooling bed) after rolling, as will be described later. Therefore, regarding the specific numerical range of Q / V for the web section cooling device 26, the relationship between the Q / V value and the amount of warpage of the hat-shaped steel sheet pile on the cooling bed is determined in advance, and the relationship is determined. It is set as the range of Q / V where the amount of warpage is within the permissible range.

The hat-shaped steel sheet pile 1 that has been finish-rolled by the finish-rolling machine 13 is sent to the downstream side by the table rollers 35 arranged along the transport direction of the hat-shaped steel sheet pile 1, but is downstream of the finish-rolling machine 13. A thermometer 31 is arranged on the side, and this thermometer 31 measures 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 type 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-mentioned temperature difference ΔT (= Tg−Tf) is desired to be within a predetermined range, the arithmetic unit 30 compares the ΔT obtained from the temperature measurement result with the target ΔT, and at the time of rolling the next material, the target ΔT is set. The opening degree setting command to the flow rate adjusting valves 25e, 26e, 26f of the joint portion cooling device 25 and the web portion cooling device 26 and the rotation speed command to the mill motor 13a of the finishing rolling mill 13 are corrected so as to be obtained.

The flow rates of the refrigerant (cooling water in this embodiment) on the surfaces of the left joint portion 4, the right joint portion 4, and the web portion 2 can be set individually. As shown in FIG. 11B, the joint shape of the hat-shaped steel sheet pile 1 is asymmetrical on the left and right sides, so that 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 individually, it is possible to deal with the case where deformation of only one joint portion becomes a problem.

Further, cooling the surface of the web portion 2 is effective in suppressing the occurrence of warpage during natural cooling on the CB (cooling bed) after rolling. If the warp is large on the CB, the transportation of the product on the CB will be hindered, and in the roller straightening performed after cooling to room temperature, the product will not bite into the roll. By cooling the surface of the web portion 2 as described above, such a problem can be suppressed.

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

Next, the background to the present invention will be described. First, for the hat-shaped steel sheet pile 1 of the present invention, the residual stress difference Δσ (= σg−σf) between the maximum residual stress σg of the joint portion 4 to the arm portion 5 and the minimum residual stress σf of the flange portion 3 is determined. The reason for the identification will be explained.
The present inventors have conducted various investigations and studies 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 which has been hot-rolled and roller-straightened under various conditions. Was done.

FIG. 5 shows that when the hat-shaped steel sheet pile 1 after finish rolling is sawed by the hot sawing device 14, the temperature profile of the hat-shaped steel sheet pile 1 in the entire width direction is measured on the entry side of the hot sawing device 14. This is an example. The temperature profile of the two rolled materials is shown, and the thick line shows the case where the joint portion 4 on the left side is experimentally cooled using water as a refrigerant in the joint portion 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. Further, it can be seen that the cooling of the joint portion 4 makes the temperature of the joint portion 4 lower than that in the case where the joint portion 4 is not cooled.

FIG. 6 shows the results of measuring the residual stress in the longitudinal direction after cold roller straightening of the hat-shaped steel sheet pile 1 commercialized from the two materials shown in FIG. 5 over the width direction. There is residual stress even after roller straightening, and there is a tensile residual stress near the center of the web portion 2 in the width direction and the vicinity of the joint portion 4, and a compressive residual stress near the flange portion 3. The product in which the joint portion 4 is cooled by the 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 in which the joint portion 4 is not cooled indicated by Δ. You can see that.

When the amount of bending of the joint portion 4 was investigated for these two products, the product without water cooling of the joint portion 4 was +6.7 mm at the joint portion 4 on the left side and +6.1 mm at the joint portion 4 on the right side. The product in which the joint portion 4 is water-cooled is +3.7 mm at the left joint portion 4 and +4.9 mm at the right joint portion 4, and the deformation of the joint portion 4 is reduced by the water cooling of the joint portion 4 in the finish rolling. It was confirmed that. As shown in FIG. 12, the bending amount of the joint portion 4 extends the joint outer edge line of the longitudinal stationary portion, and the difference in the position in the width direction between this outer extension line and the outer end of the joint portion 4 at the longitudinal end portion. The case where the end is widened is designated as a symbol +, and the case where the end is narrowed is designated as a symbol −.

Next, in order to evaluate the above findings more quantitatively, the maximum value σg of the residual stress in the vicinity of the joint portion 4 and the minimum value σf of the residual stress in the vicinity of the flange portion 3 shown in FIG. The difference σg−σf was defined 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 survey are shown in FIG. In Fig. 7, of the hat-shaped steel sheet pile 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 〇, and the 25H size with a web thickness of 13.2 mm and an effective height of 300 mm is indicated by △. ing. For residual stress, a plurality of strain gauges are attached to the front and back surfaces of the center of the hat-shaped steel sheet pile in the longitudinal direction, and these initial strains are measured. The hat-shaped steel sheet pile is cold-sawed in the width direction, and the strain after the residual stress is released by the cold-saw is measured with these strain gauges. The stress is calculated and 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 the hat-shaped steel sheet pile 1 is used, the left and right joint portions 4 are fitted as shown in FIG. 11 (c). Therefore, the bending amount of the joint portion 4 has a tolerance for fitting. In the case of the hat-shaped steel sheet pile 1, it must 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, by setting the residual stress difference Δσ (= σg−σf), which is the difference between the maximum residual stress value σg of the joint portion 4 and the minimum residual stress value σf of the flange portion 3, within the range of 0 MPa or more and 60 MPa or less. The bending amount of the joint portion 4 can be set to such an extent that there is no problem in fitting the joint. When the joint portion 4 is locally cooled and the temperature of the joint portion 4 is lower than the temperature of the arm portion 5, the maximum value of the residual stress of the arm portion 5 is larger than the maximum value of the residual stress of the joint portion 4. Can be large. In this case, even if the difference between the maximum residual stress value σg of the joint portion 4 and the minimum residual stress value σf of the flange portion 3 is 60 MPa or less, the maximum value of the residual compressive stress of the arm portion 5 and the residual value of the flange portion 3 remain. When the minimum value σf of the compressive stress exceeds 60 MPa, the bending amount of the joint portion 4 is not 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 maximum residual stress value σg of the joint portion 4 or the arm portion 5 and the minimum residual stress value σf of the flange portion 3 is 0 MPa or more. Must be 60MPa or less.

Next, the results of studies that have been able to suppress the amount of bending of the joint portion 4 by cooling the joint portion 4 and have completed the method for manufacturing the hat-shaped steel sheet pile 1 of the present invention will be described.
The difference between the maximum temperature Tg of the joint portion 4 and the minimum temperature Tf of the flange portion 3 shown in FIG. 5 is defined as the temperature difference ΔT (= Tg−Tf), and the relationship with the bending amount of the joint portion 4 in the product is defined. investigated. In addition, each of the left and right joint portions 4 was used as individual data. The results of this survey are shown in FIG. From FIG. 8, it can be seen that the bending amount of the joint portion 4 can be arranged 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.

In this way, the amount of bending of the joint portion 4 can be arranged by both the above-mentioned residual stress difference Δσ and temperature difference ΔT because, as shown in FIG. 9, ΔT and Δσ have a substantially linear correlation. be. Therefore, the relationship between the temperature difference ΔT and the bending amount at the end of the cut surface after cutting is determined, and based on this relationship, finish rolling is performed so that the range of ΔT that allows the bending amount to be within the allowable value can be obtained. By sometimes cooling the joint portion 4, the amount of bending of the joint portion 4 can be suppressed. Alternatively, the relationship between the temperature difference ΔT and Δσ is determined, and based on this relationship, rolling in the final hole type K1 of the finish rolling mill 13 is obtained so that the range of ΔT at which the residual stress difference Δσ is 0 MPa or more and 60 MPa or less can be obtained. By cooling the joint portion 4 in the above, the bending amount of the joint portion 4 can be suppressed.

The temperature difference ΔT is at the same time point after the hot rolling is completed, that is, after the rolling in the final hole type K1 of the finish rolling mill 13 is completed and the temperature of the web portion 2 drops to 500 ° C. It is 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. The temperature difference ΔT is 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, only the difference between the maximum temperature of the joint portion 4 and the minimum temperature Tf of the flange portion 3. This is because even if the range is set so that the bending can be suppressed, if the difference between the maximum temperature of the arm portion 5 and the minimum temperature Tf of the flange portion 3 is within the range where the bending cannot be suppressed, the bending cannot be suppressed. Further, the temperature difference ΔT at the same time point after the hot rolling is completed, that is, after the rolling in the final hole type K1 of the finish rolling mill 13 is completed and the temperature of the web portion 2 drops to 500 ° C. The reason for this is that after the temperature of the hat-shaped steel sheet pile 1 has dropped to a certain level or less, specifically, after the temperature of the web portion 2 has dropped to less than 500 ° C, bending has already occurred. This is because a residual stress difference has been generated. That is, unless the temperature difference ΔT at the stage of 500 ° C. or higher is adjusted at the temperature of the web portion 2, the residual stress difference Δσ cannot be changed and does not contribute to bending suppression.

Further, from the results shown in FIG. 5, the temperature difference ΔT becomes smaller as the cooling of the joint portion 4 is strengthened. 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 becomes small. However, as described above, since the cooling capacity of the joint portion 4 differs depending on the rolling speed V even if the flow rate Q is the same, it is preferable to change the flow rate Q of the cooling water 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 if the effect on ΔT is not so large when the flow rate Q is the same, then only the flow rate Q is changed without considering the rolling speed V to adjust ΔT. You may do so.

In the case of the method of adjusting the temperature difference ΔT, the temperature profile in the entire width direction of the hat-shaped steel sheet pile 1 after finish rolling is measured using the thermometer 31 described above, and the measurement result is used as a target at the time of finish rolling of the next material. It is also possible to correct the flow rate Q of the refrigerant so that ΔT can be achieved. By doing so, the control accuracy of the temperature difference ΔT is improved each time the number of rolled rolls is increased, and the bending amount can be further suppressed.

Next, an embodiment of the 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, will be described from the above findings. Using the equipment shown in FIGS. 3 and 4, various cooling conditions were applied in finish rolling, and the amount of bending of the joint portion 4 of each obtained product was investigated. An example of this survey result is shown in Fig. 10. Using water as the refrigerant, the bending amount of the joint 4 can be arranged by Q / V obtained by dividing the cooling water flow rate Q (liter / sec) of the joint 4 by the finishing rolling speed V (m / sec) of the K1 hole type. There was found.

As described above, the rolling speed is made faster than the stationary portion at the time of biting in rolling, and is adjusted by the presence or absence of bending of the product in rolling and the presence or absence of defects 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, and from this relationship, the joint portion 4 By setting the range of Q / V where the bending amount becomes the allowable range and adjusting the cooling water flow rate Q so that the Q / V is kept within a certain value range in response to the change of the rolling speed V, the joint portion 4 The amount of deformation can be kept within the allowable range.

The flow rates of the refrigerant (cooling water in this embodiment) on the surfaces of the left joint portion 4, the right joint portion 4, and the web portion 2 can be set individually. As shown in FIG. 11B, the joint shape of the hat-shaped steel sheet pile 1 is asymmetrical on the left and right sides, so that 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 individually, it is possible to deal with the case where deformation of only one joint portion 4 becomes a problem. As described above, the surface of the web portion 2 needs to be cooled when it is necessary to prevent warpage during natural cooling on the CB (cooling bed) after rolling. Therefore, by making it possible to set the flow rate of the refrigerant on the surface of the web portion 2 independently of the flow rate of the refrigerant in the joint portion 4, it is related to the flow rate of the cooling water of the joint portion 4 for suppressing the bending of the joint portion 4. It can be set depending on the presence / absence and degree of warpage.

The cooling of the surface of the web portion 2 is effective when the product length is as long as 15 m or more, for example. FIG. 13 is a schematic view showing a state in which the hat-shaped steel sheet pile 1 is warped upward. 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 a hat-shaped steel sheet pile 1 of a certain product length is used as a reference straight line, and a perpendicular line is drawn from this reference straight line to the upper surface of the web 2 in the center in the longitudinal direction. The distance between the reference straight line on this perpendicular line and the upper surface of the web 2 is defined as the amount of warpage S at the product length. Since the amount of warpage S increases almost in proportion to the square of the product length, the amount of warpage of the hat-shaped steel sheet pile 1 having a product length of 20 m on the CB (cooling bed) is large even when manufactured under the same manufacturing conditions. The amount of warpage of the hat-shaped steel sheet pile 1 having a product length of 10 m on the CB (cooling bed) is about four times as large as that of the product.

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

Further, in the CB (cooling bed) where the rolled hat-shaped steel sheet pile 1 is naturally cooled to room temperature, the bending of the joint portion 4 is confirmed, and the bending amount of the joint portion 4 is too large (when it exceeds +4 mm). Can also control the bending amount of the joint portion 4 by increasing the cooling water flow rate with respect to the subsequent rolled material, slowing down the rolling speed, or performing both of them. On the contrary, when the bending amount of the joint portion 4 is too small (= shrunk inward), it is possible to perform control such as reducing the cooling water flow rate of the joint portion 4 and increasing the rolling speed.

<Effect of embodiment>
(1) The hat-shaped steel sheet pile 1 according to one aspect of the present invention is a hat-shaped steel sheet pile 1 composed of a web portion 2, a flange portion 3, an arm portion 5, and a joint portion 4, and is a joint portion 4 to an arm portion. The residual stress difference Δσ (= σg−σf), which is the difference between the maximum residual stress value σg of 5 and the minimum residual stress value σf of the flange portion 3, is 0 MPa or more and 60 MPa or less.
According to the configuration (1) above, the amount of bending at the end of the cut surface after cutting the hat-shaped steel sheet pile 1 along the width direction can be set to such an extent that there is no problem in fitting the joint.

(2) In the method for manufacturing the hat-shaped steel sheet pile 1 according to one aspect of the present invention, the hat-shaped steel sheet pile 1 composed of the web portion 2, the flange portion 3, the arm portion 5 and the joint portion 4 is hot-rolled. In the method for manufacturing the hat-shaped steel sheet pile 1 which is formed into the shape of the hat-shaped steel sheet pile 1 and then cut in the width direction, after the hot rolling is completed 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 point is defined as a temperature difference ΔT (= Tg−Tf), and the temperature difference ΔT and the cutting are performed. The relationship with the bending amount at the end of the cut surface is determined, and based on this relationship, the final hole type K1 of the finishing rolling mill 13 is provided so that the range of ΔT that allows the bending amount to be within the allowable value can be obtained. It is characterized in that the joint portion 4 is cooled in rolling.
According to the configuration of (2) above, the hat-shaped steel sheet pile 1 has a bending amount at the end of the cut surface after cutting the hat-shaped steel sheet pile 1 along the width direction so that there is no problem in fitting the joint. Can be manufactured.

(3) In the method for manufacturing the hat-shaped steel sheet pile 1 according to one aspect of the present invention, the hat-shaped steel sheet pile 1 composed of the web portion 2, the flange portion 3, the arm portion 5 and the joint portion 4 is hot-rolled. In the method for manufacturing a hat-shaped steel sheet pile 1 which is formed into the shape of the hat-shaped steel sheet pile 1 and then cut in the width direction, after the hot rolling is completed 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 point is the temperature difference ΔT (= Tg−Tf), and the residual of the joint portion 4 to the arm portion 5. The difference between the maximum stress value σg and the minimum residual stress value σf of the flange portion 3 is defined as the residual stress difference Δσ (= σg−σf), and the relationship between the temperature difference ΔT and the residual stress difference Δσ is defined and this relationship is established. Based on the above, the joint portion 4 is cooled in rolling with the final hole type K1 of the finish rolling mill 13 so that the range of ΔT that allows the residual stress difference Δσ to be 0 MPa or more and 60 MPa or less can be obtained.
According to the configuration of (3) above, the hat-shaped steel sheet pile 1 has a bending amount at the end of the cut surface after cutting the hat-shaped steel sheet pile 1 along the width direction so that there is no problem in fitting the joint. Can be manufactured.

(4) In the method for manufacturing a hat-shaped steel sheet pile according to one aspect of the present invention, the hat-shaped steel sheet pile 1 composed of a web portion 2, a flange portion 3, an arm portion 5 and a joint portion 4 is hot-rolled. In the method for manufacturing a hat-shaped steel sheet pile 1 that is formed into the shape of a hat-shaped steel sheet pile 1 and then cut in the width direction, the joint portion 4 is cooled in rolling with the final hole type K1 of the finish rolling mill 13 and cooled. The relationship between the value Q / V obtained by dividing the flow rate Q per unit time of the refrigerant for which the above-mentioned method is performed by the rolling speed V at the time of rolling by the finishing rolling mill 13 and the bending amount of the cut surface end portion after cutting is obtained in advance. From the relationship, the range of the value Q / V at which the bending amount is within the permissible range is set, and the value Q / V is set within the set range in accordance with the change of the rolling speed V. It is characterized in that the flow rate Q of the refrigerant per unit time is adjusted.
According to the configuration of (4) above, the hat-shaped steel sheet pile 1 has a bending amount at the end of the cut surface after cutting the hat-shaped steel sheet pile 1 along the width direction so that there is no problem in fitting the joint. Can be manufactured.

(5) In any of the above configurations (2) to (4), the joint portion 4 is cooled individually 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, a temperature difference is likely to occur between the left and right joint portions 4, but according to the configuration of (5) above, the left and right joint portions 4 are cooled. By setting them individually, it is possible to deal with the case where deformation of only one joint portion 4 becomes a problem.

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

(7) In the hat-shaped steel sheet pile manufacturing equipment according to one aspect of the present invention, the hat-shaped steel sheet pile 1 composed of the web portion 2, the flange portion 3, the arm portion 5 and the joint portion 4 is hot-rolled. A hot rolling mill (rough rolling mill 11, intermediate rolling mill 12, and finish rolling mill 13) that forms the shape of the hat-shaped steel sheet pile 1 and a hat-shaped steel sheet pile 1 obtained by the hot rolling are placed in the width direction. In the manufacturing equipment of the hat-shaped steel sheet pile 1 having the saw cutting device (hot saw cutting device 14) for cutting, the joint portion 4 is placed in the guide (front guide 23) of the finish rolling mill 13 of the hot rolling mill. A joint portion cooling device 25 for cooling is provided, the joint portion cooling device 25 can adjust the flow rate Q of the refrigerant for cooling the joint portion 4 per unit time, and the finishing rolling mill 13 can adjust the rolling speed V. It is characterized by having a recording means for recording the actual results of the flow rate Q and the rolling speed V.
According to the configuration of (7) above, the flow rate Q of the refrigerant that cools the joint portion 4 and the finish rolling, which affect the bending amount of the cut surface end portion after cutting the hat-shaped steel sheet pile 1 along the width direction. Since the rolling speed V of the machine 13 can be adjusted and the actual results of the flow rate Q and the rolling speed V can be recorded, it is optimal from the relationship between the bending amount at the end of the cut surface, the flow rate Q, and the rolling speed V with the saw cutting 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 point between the completion of the hot rolling and the temperature drop of the web portion 2 to 500 ° C. Per unit time of the refrigerant from the joint cooling device 25 so that the temperature difference ΔT (= Tg−Tf), which is the difference from the maximum temperature Tg of 4 to the arm 5, is within a preset allowable value. It is characterized in that it is provided with a flow rate control means for setting the flow rate Q of the above.
According to the configuration of (8) above, the hat-shaped steel sheet pile 1 has a bending amount at the end of the cut surface after cutting the hat-shaped steel sheet pile 1 along the width direction so that there is no problem in fitting the joint. Can be manufactured.

(9) In the configuration of (8) above, the temperature in the entire width direction of the hat-shaped steel sheet pile 1 is located on the downstream side of the finishing rolling mill 13 and upstream of the position where the temperature of the web portion 2 drops to 500 ° C. The thermometer 31 for measuring the distribution is provided, and the flow control means is characterized in that the flow rate Q of the refrigerant is corrected at the time of 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 each time the number of rolled sheets is increased, and the hat-shaped steel sheet pile 1 can be manufactured to the extent that there is no problem in fitting the joint.

(10) In the configuration of (7) above, the bending amount is permissible from the relationship between the value Q / V obtained by dividing the flow rate Q by the rolling speed V and the bending amount at the end of the cut surface after cutting. The range of the value Q / V within the range is set in advance, and the flow rate Q per unit time of the refrigerant is set so as to keep the value Q / V within the set range in response to the change in the rolling speed V. It is characterized by having a flow rate control means for adjusting.
According to the configuration of (10) above, the hat-shaped steel sheet pile 1 has a bending amount at the end of the cut surface after cutting the hat-shaped steel sheet pile 1 along the width direction so that there is no problem in fitting the joint. Can be manufactured.

(11) In the configuration of the above (7) to (10), in addition to the joint portion cooling device 25, the web portion cooling device 26 for cooling the web portion 2 is provided in the guide (front guide 23). It is a feature.
According to the configuration (11) above, it is possible to manufacture the hat-shaped steel sheet pile 1 in which the occurrence of upward warpage when the hat-shaped steel sheet pile 1 is naturally cooled on the CB (cooling bed) after rolling is suppressed.

<Example 1>
At the rolling production line of the hat-shaped steel sheet pile shown in FIGS. 1, 2, 2, and 4, the hat-shaped steel sheet pile 10H having a web thickness of 10.8 mm and an effective width of 900 mm was manufactured.
A thermometer 31 is placed in front of the hot saw cutting 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 by 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, based on the relationship between the temperature difference ΔT shown in FIG. 8 and the bending amount of the joint portion 4, the target value is 40 ° C. and the target range is 30 to 50 as the range of ΔT that allows the bending amount to be within the allowable value (± 4 mm). The temperature was set to ℃, and the flow rate of the cooling water at the joint was adjusted individually for each of the left and right sides during the finish rolling in the K1 hole type. On the other hand, in the comparative example, a case where the joint portion was not cooled at all (Comparative Example 1) and a case where the joint portion was cooled at the maximum flow rate (Comparative Example 2) were carried out. Since the temperature profile changes from moment to moment with the passage of time during sawing with the hot sawing device 14, the temperature difference ΔT was calculated from the temperature profile when the maximum temperature of the web portion 2 was 550 ° C. The finish rolling speed is 2 m / s in all cases.

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

From the results in Table 1, the target of the difference ΔT between the maximum temperature of the joint portion 4 and the minimum temperature of the flange portion 3 is set from the relationship between the temperature difference ΔT and the bending amount of the joint portion, and the temperature difference ΔT follows this target. In the conforming example in which the joint portion 4 is cooled as described above, 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 portion 4 was improper, the bending amount of the joint portion 4 was not satisfied within ± 4 mm.

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

From the results in Table 2, from the relationship between the Q / V value shown in FIG. 10 and the bending amount of the joint portion 4, 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. In the conforming example in which the cooling water flow rate of the joint portion 4 is adjusted with the allowable range of 1.6 to 2.4, the bending amount of the joint portion 4 is within ± 4 mm under 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, the bending amount of the joint portion 4 may be within ± 4 mm depending on the finish rolling speed condition (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 achieved within ± 4 mm due to changes in the finish rolling speed.

<Example 3>
In the rolling production line of the hat-shaped steel sheet pile 1 shown in FIGS. 1, 2, 3 and 4, the product length of the hat-shaped steel sheet pile 25H having a web thickness of 13.2 mm and an effective width of 900 mm is 20 m. We carried out the production of long products. In manufacturing, the rolling speed in the K1 hole type rolling, which is the final finishing rolling, is 2.0 m / s, and the value (Q / V) obtained by dividing the joint cooling water amount Q by the rolling speed V is 2.0 (L / s). ) / (M / s). Then, three bottles were produced for each of the case where the web cooling was performed with the web cooling water amount Qw set to 4.0 (L / s) and the case where the web cooling was not performed.

As a result, the bending amount of the joint portion 4 was satisfied within ± 4 mm in all of the three products manufactured by web cooling and the three products manufactured without web cooling. On the other hand, when web cooling was performed, the amount of warpage on the CB was 50 mm or less for all three products, and there was no particular problem, whereas when web cooling was not performed, the amount of warpage of all three products was 50 mm or less. The S became very large, 200 mm or more, and the product was skewed during product transportation in the CB, and contact and overlap with adjacent products occurred. For this reason, for products that have not been web-cooled, the operator has to use an overhead crane to correct the transport state on the CB, and the manufacturing pitch has been reduced during that time.

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 rolling mill (hot rolling mill)
13a Mill motor 14 Hot sawing device (saw cutting device: hot saw HS)
21 Top rolling roll 22 Bottom 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 adjustment valve (joint cooling water flow adjustment valve)
26 Web part cooling device 26a Web top surface cooling header 26b Web top surface cooling nozzle 26c Web bottom surface cooling header 26d Web bottom surface cooling nozzle 26e Flow control valve (Web top surface cooling water flow rate adjustment valve)
29 Cooling water pump 30 Arithmetic logic unit (flow control means)
31 thermometer

Claims (3)

In a method for manufacturing a hat-shaped steel sheet pile, which is formed by hot rolling 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, and then cut in the width direction. ,
The difference between the minimum temperature Tf of the flange portion and the maximum temperature Tg of the joint portion or the arm portion at the same time point after the completion of the hot rolling until the temperature of the web portion drops to 500 ° C. is the temperature. The difference ΔT (= Tg−Tf) is set, and the relationship between the temperature difference ΔT and the bending amount at the end of the cut surface after the cutting is determined, and based on this relationship, the bending amount is set to ± 4 mm or less. as the range 30 to 50 ° C. is obtained, in the rolling of the final hole-type finishing mill, dividing the flow rate Q per unit of refrigerant for cooling time rolling speed V at the time of rolling by the finishing mill A method for manufacturing a hat-shaped steel sheet pile , which comprises controlling the value of 1.6 to 2.4 to cool the joint portion. The method for manufacturing a hat-shaped steel sheet pile according to claim 1, wherein the joint portions are cooled individually for the left and right joint portions. The method for manufacturing a hat-shaped steel sheet pile according to claim 1 or 2, wherein the web portion is cooled in addition to cooling the joint portion.

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