Method for manufacturing steel sheet pile and rolling equipment assembly for manufacturing steel sheet pile

Abstract

The present invention provides a method for manufacturing a large steel sheet pile with a high height. A rolling equipment group in which a heating device, a rough rolling mill, an intermediate rolling mill and a finishing rolling mill are sequentially arranged is used to heat the raw material, and a plurality of rolling passes based on the hole profile are performed to form a steel sheet pile of a predetermined shape. At this time, in the intermediate rolling, a hole profile is used to perform rolling in such a manner that the shape after the intermediate rolling becomes a first shape in which the flange portion is bent or folded outward. As a result, the depth of the engraved hole profile can be made shallower, the decrease in the bending resistance of the roller can be suppressed, and the use range of the roller is increased. In addition, in the finishing rolling immediately following the intermediate rolling, the bending forming is performed in such a manner that the flange portion of the first shape becomes a straight shape or a second shape that is bent or folded inward.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a steel sheet pile and a rolling equipment group for manufacturing the steel sheet pile, and in particular to a method for manufacturing a high-height steel sheet pile and a rolling equipment group for manufacturing the steel sheet pile. Background Art

[0002] Preferred steel sheet piles as fence members for civil engineering include hat-shaped steel sheet piles, U-shaped steel sheet piles, and the like. Figure 1 The hat-shaped steel sheet piles ( Figure 1 (a)) and U-shaped steel sheet piles ( Figure 1 The cross-sectional shape of (b) is an example of a product shape.

[0003] The steel sheet pile 1 is usually made of slabs, billets, etc. Figure 2 The steel sheet pile is manufactured by a rolling equipment group 2 shown in the figure. In such a rolling equipment group 2, the raw material is loaded into the heating device 3, and after being heated to a predetermined temperature, for example, 1300°C, the heated raw material is conveyed in the order of a rough rolling mill 4, an intermediate rolling mill 5, and a finishing rolling mill 6, and rolled to a predetermined cross-sectional shape, thereby forming a product shape. It should be noted that the rolling in the rough rolling mill 4 is also called rough rolling, the rolling in the intermediate rolling mill 5 is called intermediate rolling, and the rolling in the finishing rolling mill 6 is called finishing rolling. These rolling mills are equipped with rolls with a hole type called a roll hole type engraved on the upper roll and the lower roll. It should be noted that, hereinafter, the upper roll and the lower roll are also collectively referred to as upper and lower rolls or a roll group.

[0004] Figure 3 An example of the hole profiles engraved on the upper and lower rolls of the rough rolling mill 4 used in the rough rolling of the hat-shaped steel sheet pile is shown. Three hole profiles, Box hole profile 71, K8 hole profile 72 and K7 hole profile 73, are engraved on the upper roll 41 and the lower roll 42. In the rough rolling using this hole profile, a slab is used as a raw material, and first, the width of the slab is pressed down with the Box hole profile 71. Next, the slab is bent and deformed into a hat shape and the thickness is pressed down with the K8 hole profile 72. Furthermore, the thickness is pressed down with the K7 hole profile 73, and the raw material is molded into a shape close to the cross-sectional shape of the product. It should be noted that multiple passes of rolling are performed in the K8 hole profile 72 and the K7 hole profile 73, respectively.

[0005] The intermediate rolling mill 5 used for the intermediate rolling also includes rolls having about 2 to 4 grooves engraved on upper and lower rolls, similarly to the rough rolling mill 4 . Figure 4 An example of the hole pattern engraved on the upper and lower rolls of the intermediate rolling mill 5 used in the intermediate rolling of the hat-shaped steel sheet pile is shown. Figure 4In the example, two pass types, K3 pass type 75 and K6 pass type 74, are engraved on the upper roll 51 and the lower roll 52. It should be noted that, although not particularly shown in the figure, two pass types, K4 pass type 77 and K5 pass type 76, are also engraved on the upper and lower rolls of the other intermediate rolling mill 5. In the intermediate rolling, the raw material after rough rolling is rolled in sequence with these pass types to reduce the thickness and form the shape, thereby forming the raw material into a shape closer to the cross-sectional shape of the product.

[0006] The finishing mill 6 used for the finishing rolling also has about 1 to 3 grooves engraved on the upper and lower rolls. Figure 5 An example of the hole pattern engraved on the upper and lower rolls of the finishing mill 6 used for the finish rolling of the hat-shaped steel sheet pile is shown. Figure 5 In the embodiment, the upper roll 61 and the lower roll 62 are provided with two hole types, K2 hole type 78 and K1 hole type 79. In the finishing rolling, the raw material after the intermediate rolling is subjected to the final thickness reduction by the K2 hole type 78, and then the joint portion 14 is bent and formed by the K1 hole type 79, thereby shaping the raw material into the cross-sectional shape of the final product.

[0007] It should be noted that in the intermediate rolling and the finish rolling, the number of rolling passes for each pass type is basically one, and the number of rolling passes for the same pass type is set to about 2 or 3 passes in a large number of cases.

[0008] Moreover, similarly to the hat-shaped steel sheet pile, the U-shaped steel sheet pile is also manufactured by passing through a plurality of rolling mills and performing groove rolling so as to gradually obtain a product cross-sectional shape.

[0009] Recently, there is a trend toward increasing the size of such steel sheet piles in order to improve rigidity and section modulus and to improve workability.

[0010] In response to such a tendency, for example, Patent Document 1 describes a "roll forming device" for forming a lightweight steel sheet pile with a large height dimension. The "roll forming device" described in Patent Document 1 is a roll forming device that is sequentially composed of a claw forming rolling stand, a front half bending forming rolling stand, a rear half bending forming rolling stand, and a shape determining rolling stand. The claw forming rolling stand is composed of a pair of upper and lower horizontal grooved rollers with claws pre-formed at both ends of a flat raw material. In addition, the front half bending forming rolling stand has: a pair of upper and lower horizontal flat rollers that press down only the web portion of the lightweight steel sheet pile; and a pair of upper and lower horizontal V-bending rollers that are provided on roller shafts that are independent of the above-mentioned flat rollers and perform bending forming of the second bent portion. In the front half bending forming rolling stand, a part of the forming of the first bent portion and a large part of the forming of the second bent portion are performed. In addition, the rear half bending forming rolling stand has: a pair of upper and lower horizontal flat rollers that sandwich the web portion; an inclined roller that is provided on an inclined roller shaft and contacts the outer side surface of the flange portion; and a receiving roller that receives the lower surface side of the second bent portion. In Patent Document 1, the final forming of the first bent portion is performed in the rear half bending forming rolling stand. In Patent Document 1, the shape determining rolling stand has a pair of upper and lower grooved rollers that form the groove of the final cross-sectional shape in the same manner as in the past, and the product is formed. According to the roll forming device described in Patent Document 1, even when forming a cross-sectional shape with a large height dimension, the roll diameter can be greatly reduced.

[0011] In addition, Patent Document 2 describes a "method for manufacturing steel sheet piles". The technology described in Patent Document 2 is a method for manufacturing steel sheet piles in which a hat-shaped or U-shaped steel sheet pile is manufactured by hot rolling and then the steel sheet pile is formed by cold working to form a steel sheet pile having a different cross-sectional shape. In the technology described in Patent Document 2, the cold working is preferably a process of widening or narrowing the width direction of the steel sheet pile, or a process of making the angle of the corner of the steel sheet pile a wide angle or a narrow angle. According to the technology described in Patent Document 2, even steel sheet piles that cannot be manufactured by the same hot rolling equipment can be manufactured, and steel sheet piles with a high degree of freedom can be manufactured.

[0012] In addition, Patent Document 3 describes a "method for manufacturing a groove-shaped material". The technique described in Patent Document 3 is a "method for manufacturing a groove-shaped material" that sequentially performs a rough rolling process and a finishing process. Here, in the rough rolling process of Patent Document 3, a groove rolling process is performed on a rolling material heated to a predetermined temperature by a plurality of sets of double rollers formed with a predetermined groove, thereby manufacturing an intermediate product. At this time, the cross-sectional shape of the rolling material is made into a convex shape in which a pair of flange portions are respectively inclined outward relative to a vertical line and a web portion protrudes toward the flange portion, the central portion thereof is flat, the two ends of the web portion are connected to the flange portion approximately perpendicularly, and the wall thickness of the flange portion and the web portion is set to be approximately the same thickness as the product size, thereby forming an intermediate product. Next, in the rough rolling process, after the front end portion of the flange portion of the intermediate product is formed into a concave shape having a middle raised portion bulging in the thickness direction in the cross-sectional shape by a four-axis roller, the front end portion of the flange portion is rolled in the thickness direction to perform adjustment to improve the flatness of the flange portion. Furthermore, the finishing process is a process of forming the web portion of the intermediate product in the shape of a convex portion by using a plurality of forming rollers arranged in parallel to each other, and forming a groove-shaped material having a flange portion perpendicular to the web portion and substantially parallel to each other and a flat web portion by roller processing (cold, warm, hot). In the technology described in Patent Document 3, even for a raw material with low thermal deformation energy, the generation of surface defects can be suppressed and the flatness of the end surface of the front end portion of the flange portion can be improved.

[0013] In addition, Patent Document 4 describes a "method for manufacturing channel steel". In the "method for manufacturing channel steel" described in Patent Document 4, channel steel is manufactured by rolling in sequence using a plurality of pairs of horizontal hole-shaped rollers. At this time, a plate thickness difference of [web>flange] is preliminarily given to the web and flange of the rolled material before the pre-finishing pass, and the web and flange are rolled in a curved shape. Between the pre-finishing pass and the final finishing pass, the rollers are not brought into contact with the flange, and hot rough forming is performed to reduce the opening angle of the flange. Next, in Patent Document 4, after passing the final finishing pass, the bending correction of the rolled material is performed using hot correction. In the technology described in Patent Document 4, high-alloy steel channel steel can be mass-produced simply and at low cost without causing roller sliding defects.

[0014] In addition, Patent Document 5 describes a "Method for Manufacturing Hot-Rolled Channel Steel". The technique described in Patent Document 5 is a method for manufacturing hot-rolled channel steel by performing a hot rolling process and a forming process, wherein the hot rolling process uses a plurality of sets of rolls formed with a predetermined pass shape to manufacture a W-shaped workpiece intermediate material by hot rolling, wherein the workpiece intermediate material has: a web portion having a curved surface shape with concave and convex surfaces on the front and back; and flange portions extending substantially perpendicularly from the left and right ends of the web portion, respectively, and the forming process manufactures a U-shaped channel steel from the manufactured W-shaped workpiece intermediate material by bending. In the technique described in Patent Document 5, the forming process is set as a rough forming process by hot forming, and the rough forming process uses a first roller that contacts the concave surface of the web portion of the workpiece intermediate material, and a second roller that contacts the central protrusion of the convex surface of the web portion and has a gap with the end portion near the end portion closer to the central protrusion. It should be noted that in the rough forming process, it is preferred that the flange portion is pressed inward by a pair of left and right guide rollers provided on the left and right sides of the first roller and the second roller to promote the above-mentioned bending forming. According to the technology described in Patent Document 5, it is possible to continuously perform hot working and produce hot-rolled channel steel of excellent quality.

[0015] Prior Art Literature

[0016] Patent Literature

[0017] Patent Document 1: Japanese Patent Application Laid-Open No. 07-088562

[0018] Patent Document 2: Japanese Patent Application Publication No. 2003-230916

[0019] Patent Document 3: Japanese Patent Application Laid-Open No. 04-066202

[0020] Patent Document 4: Japanese Patent Application Laid-Open No. 05-154502

[0021] Patent Document 5: Japanese Patent Application Publication No. 2001-276902 Summary of the invention

[0022] Summary of the Invention

[0023] Problems to be solved by the invention

[0024] However, the technology described in Patent Document 1 is limited to the manufacture of lightweight steel sheet piles based on cold bending, and requires cold roll forming equipment with a complex structure. Moreover, the technology described in Patent Document 2 has the problem of requiring cold working equipment in addition to hot rolling equipment. Moreover, the technologies described in Patent Documents 3 to 5 are methods for manufacturing channel steel or channel materials. In these rolling methods for channel steel (channel materials), there are problems such as unstable bending forming of the web and flange parts, and it is difficult to apply to steel sheet piles that require claw formation of the joint part in the final stage of hot rolling. In addition, recently, large steel sheet piles such as those with an effective width W of 900 mm and an effective height H exceeding 300 mm are desired.

[0025] In order to roll a steel sheet pile with a high effective height H (hereinafter also referred to as a "high-height" steel sheet pile), it is necessary to use a roller with a deep hole profile for forming (rolling). However, if the roller is engraved with a deep hole profile, the diameter of the small diameter portion of the roller is too small, and the bending resistance of the roller during rolling decreases. Moreover, in the rolling of a steel sheet pile with a high effective height H and a wide effective width W, if rolling is performed under the same reduction conditions as the conventional steel sheet pile with a narrow effective width, the rolling load and the rolling torque increase. When manufacturing large steel sheet piles, such a decrease in the bending resistance of the roller overlaps with the increase in the rolling load, causing the roller to be damaged during rolling, and it may become impossible to roll. Moreover, since the roller is engraved with a deep hole profile, the diameter of the small diameter portion of the roller is too small, and there is also a problem that the effective use margin (effective use range) of the roller is greatly reduced.

[0026] The present invention solves the problems of the prior art as described above, and aims to provide a method for manufacturing a steel sheet pile that can manufacture a high-height steel sheet pile only by a hot rolling process without using cold rolling, and a rolling equipment group for manufacturing a steel sheet pile. It should be noted that the "high-height" steel sheet pile referred to here refers to a large steel sheet pile having an effective width W of 900 mm or more and an effective height H of more than 300 mm, preferably 350 mm or more.

[0027] Solutions to Solve Problems

[0028] In order to achieve the above-mentioned purpose, the inventors have carefully studied a method for manufacturing a high steel sheet pile without using a deep-pass roll. As a result, they thought of a case where the flange portion is rolled in a shape that is bent or folded outward in a rolling pass where the rolling load is likely to become large relative to the pass depth, for example, in a part of rough rolling and in intermediate rolling. That is, they found that after the intermediate rolling, if the flange portion is rolled in a shape that is bent or folded outward, the pass of the roll can be formed into a shallow pass compared to the case where the flange portion is a straight line, and the reduction in the bending resistance of the roll can be prevented, and the use margin (effective use range) of the roll can be increased.

[0029] The present invention is the result of further research based on the above findings.

[0030] [1] A method for manufacturing a steel sheet pile, using a plurality of hole dies to sequentially perform rough rolling, intermediate rolling and finish rolling on a heated raw material to manufacture a steel sheet pile having a flange portion of a specified shape, wherein in the intermediate rolling, the flange portion is rolled in such a manner that the shape of the flange portion after the intermediate rolling becomes a first shape bent or folded outward, and in the finish rolling immediately following the intermediate rolling, the flange portion of the first shape is bent into a straight shape or a second shape bent or folded inward.

[0031] [2] The method for manufacturing a steel sheet pile according to [1], wherein the rolling pass in which the bending forming is performed in the finish rolling is a rolling pass using a web guide on the rolling feed side.

[0032] [3] A method for manufacturing steel sheet piles according to [2], wherein the web guide has, in a cross section perpendicular to the rolling direction, an upper surface width of the web guide that is equal to or narrower than the lower surface width of the web of the raw material after the final rolling pass of the intermediate rolling, and an angle between the upper surface of the web guide and the side surface of the web guide that is equal to the angle formed by the joint between the web portion and the flange portion of the raw material after the final rolling pass of the intermediate rolling.

[0033] [4] The method for manufacturing a steel sheet pile according to any one of [1] to [3], wherein in the finish rolling, claw bending is performed in a rolling pass immediately following the rolling pass in which the bending is performed.

[0034] [5] The method for manufacturing a steel sheet pile according to [4], wherein a claw bending pre-forming is performed on the delivery side of the rolling pass in which the bending forming is performed in the finish rolling, and then the claw bending forming is performed.

[0035] [6] A rolling equipment group for manufacturing steel sheet piles, which is a rolling equipment group for manufacturing steel sheet piles that is formed by arranging a heating device, a rough rolling mill, an intermediate rolling mill and a finishing rolling mill in sequence, wherein the rough rolling mill, the intermediate rolling mill and the finishing rolling mill are rolling mills each having an upper and lower roll with a hole pattern engraved thereon, and the hole pattern of at least the entirety or a portion of the downstream side of the intermediate rolling mill is a hole pattern engraved in such a manner that a flange portion is formed into a first shape that is bent or folded outward, and the hole pattern of a portion of the finishing rolling mill is a hole pattern engraved in such a manner that the flange portion of the first shape is bent into a straight shape, or into a second shape that is bent or folded inward.

[0036] Effects of the Invention

[0037] According to the present invention, steel sheet piles having a high effective height and a large effective width can be easily, stably and productively manufactured without accidents such as roll breakage by only using a hot rolling process without using cold rolling, thereby exerting a special effect in industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is an explanatory diagram schematically showing an example of the product shape of a steel sheet pile. Figure 1 (a) is an example of a hat-shaped steel sheet pile. Figure 1 (b) is an example of a U-shaped steel sheet pile.

[0039] Figure 2 This is an explanatory diagram showing an example of a rolling facility for manufacturing steel sheet piles.

[0040] Figure 3 This is an explanatory diagram showing an example of a rough rolling pass (cross section) used in the production of a hat-shaped steel sheet pile.

[0041] Figure 4 This is an explanatory diagram showing an example of an intermediate rolling pass (cross section) used in the production of a hat-shaped steel sheet pile.

[0042] Figure 5 This is an explanatory diagram showing an example of a pass profile (cross section) for finish rolling used in the production of a hat-shaped steel sheet pile.

[0043] Figure 6 This is a cross-sectional view showing an example of a rough rolling pass K7 suitable for producing a hat-shaped steel sheet pile in the present invention.

[0044] Figure 7 This is a cross-sectional view showing an example of an intermediate rolling pass K3 suitable for producing a hat-shaped steel sheet pile in the present invention. Figure 7 (a) shows an example where the flange is bent outward. Figure 7 (b) shows an example in which the flange portion is bent outward.

[0045] Figure 8 This is a cross-sectional view showing an example of a finish rolling pass K2 suitable for producing a hat-shaped steel sheet pile in the present invention.

[0046] Fig. 9 This is an explanatory diagram schematically showing an example of the product shape of a steel sheet pile.

[0047] Fig.10 It is a cross-sectional view schematically showing the bending return forming state of the flange portion during finish rolling.

[0048] Fig.11 It is an explanatory diagram schematically showing a web guide. Fig.11(a) shows the shape of the web guide, Fig.11 (b) shows the arrangement position of the web guide.

[0049] Fig.12 This is an explanatory diagram schematically showing an example of a claw bending roller. DETAILED DESCRIPTION

[0050] In one embodiment of the present invention, for example, using Figure 2 The rolling mill group 2 shown manufactures the steel sheet pile 1 .

[0051] In this embodiment, a raw material (steel raw material; for example, a rectangular slab) is charged into a heating device 3 and heated to a predetermined temperature, for example, 1300° C. Then, the heated raw material is sequentially conveyed to a roughing mill 4, an intermediate rolling mill 5, and a finishing mill 6 for rolling, for example, to produce Figure 1 The cross-sectional shape of the hat-shaped steel sheet pile 1A shown in (a) is shown in FIG. In addition, in the rolling equipment group 2, by rolling a plurality of raw materials in sequence, it is possible to continuously manufacture products (hat-shaped steel sheet piles 1A) of the same size.

[0052] During the rolling (rough rolling) of the rough rolling mill 4, as Figure 3 As shown, the raw material after heating is rough-rolled by three hole types, namely, the Box hole type 71, the K8 hole type 72 and the K7 hole type 73, which are engraved on the upper and lower rollers 41 and 42 of the rough rolling mill 4. Multiple passes of rolling are respectively performed in the K8 hole type 72 and the K7 hole type 73. In the rough rolling, the slab is used as the raw material. First, the width of the raw material (slab) is pressed down by the Box hole type 71, and then it is rotated 90°. The slab is bent into a hat shape by the K8 hole type 72, and the thickness is pressed down (thickness reduction) is performed. Then, the thickness is continuously pressed down and the joint part is roughly formed by the K7 hole type 73, and the shape is formed into a shape close to the cross-sectional shape of the product. It should be noted that the height H7 of the K7 hole type 73 is engraved to be larger than the height H8 of the K8 hole type 72, and the flange part is also stretched and deformed in the K7 hole type 73.

[0053] In addition, if Figure 6 As shown, in the K7 pass 731, the flange portion may be rolled into a shape that is bent outward by engraving. It should be noted that the flange portion may also be rolled into a shape that is bent outward. However, in the rough rolling stage, in rolling passes other than the rolling pass where the roll strength is likely to become a problem due to the deep pass depth relative to the rolling load, it is not necessary to roll the flange portion in a shape that is bent or bent outward.

[0054] Next, the raw material (intermediate raw material) formed by rough rolling is rolled (intermediate rolling) using the grooves engraved on the upper and lower rolls of the intermediate rolling mill 5. Figure 2 In the rolling equipment group 2 shown, two rolling mills (two roll groups) can also be configured as an intermediate rolling mill 5 to perform tandem rolling with two pass types arranged along the rolling direction. In this rolling (intermediate rolling), the thickness of the raw material is mainly reduced, but tensile deformation of the flange portion can also be applied.

[0055] In the present invention, rolling is performed so that the shape after intermediate rolling becomes the first shape in which the flange portion is bent or folded outward. The flange portion of the first shape means the flange portion that is bent or folded outward after intermediate rolling.

[0056] In a rolling pass in which the rolling load tends to increase with respect to the hole depth, the raw material is rolled using a hole profile engraved on the upper and lower rollers (roller group) in such a manner that the flange portion becomes a shape bent or bent outward. Examples of such rolling passes in which the rolling load tends to increase with respect to the hole depth include, for example, a part of the rolling passes of rough rolling, all the rolling passes of intermediate rolling, or a part of the rolling passes on the downstream side. In the present invention, it is preferred that after intermediate rolling, a hole profile engraved on the upper and lower rollers (roller group) in such a manner that the flange portion becomes a shape bent or bent outward. As the hole profile to be used, for example, it is preferred in rough rolling. Figure 6 The groove shape engraved in such a way that the flange portion becomes a shape bent outward as shown is preferably used in the intermediate rolling. Figure 7 The hole pattern is engraved in such a way that the flange portion is curved outward as shown in (a) in FIG. Figure 7 The hole is engraved in such a way that the flange portion is bent outward as shown in (b) in the figure. As a result, the height H of the hole can be reduced compared to the case where the flange portion is a straight line. Figure 7 H3 in the middle), the effective usage margin (effective usage range) of the roller is increased.

[0057] The intermediate rolling mill 5 has, for example, a K3 pass 751 (see Figure 7 The second intermediate rolling mill includes rolls with two pass types, K5 pass type 761 and K4 pass type 771, which are engraved on the upper and lower rolls, respectively, although not shown. The intermediate rolling mill includes rolls with two pass types, K6 pass type 741 and K6 pass type 741 (not shown), which are engraved on the upper and lower rolls, respectively, and K5 pass type 761 and K4 pass type 771, which are engraved on the upper and lower rolls, respectively. The intermediate rolling mill includes rolling including tandem rolling in sequence for the raw material after the rough rolling, using these pass types engraved so that the flange portion becomes a shape that is bent or folded outward after the intermediate rolling.

[0058] It should be noted that when the height H of the hole type used in the intermediate rolling is set according to the order of rolling passes, for example, H6 under the K6 hole type, H5 under the K5 hole type, H4 under the K4 hole type, and H3 under the K3 hole type, it is preferred to set the height of the hole type in a manner that satisfies the following formula (1).

[0059] H6≤H5≤H4≤H3......(1)

[0060] By setting the height of the pass used for the intermediate rolling so as to satisfy the formula (1), the flange portion can be subjected to tensile deformation in sequence at each pass, and an effect that a high-height steel sheet pile material can be stably rolled can be expected.

[0061] Next, the intermediate material shaped by the intermediate rolling is further rolled (finish rolling) by the grooves engraved on the upper and lower rolls of the finishing mill 6 .

[0062] The finishing mill 6 includes an upper roll 61 and a lower roll 62 with a K2 groove 78 (see Figure 8 ) and K1 pass 79 (not shown). In the finish rolling of this embodiment, the flange portion is bent and returned to form a straight shape using the K2 pass 78 through the first rolling pass. The K2 pass 78 is a pass engraved on the upper and lower rolls in such a way that the flange portion is in a straight shape. It should be noted that in the K2 pass, it is preferred that the web lower surface width ( Figure 8 B2) and K2 groove type before rolling web lower surface width ( Figure 7 B3) is equal, and the angle between the web and the flange of the K2 hole type is ( Figure 8 θ2) is equal to the angle between the web and the flange before K2 groove rolling ( Figure 7 θ3). As a result, when the flange portion is bent and returned, the raw material will not deviate in the vertical direction or the horizontal direction, and the flange portion can be bent and returned stably.

[0063] It should be noted that, in the above description, the flange portion is described as a straight line in the final product shape, but the flange portion in the product shape may be a shape other than a straight line. Fig. 9 As shown schematically in the cross-sectional shape, the flange portion is formed into a shape that is bent or folded inward as the final product shape. In this case, the K2 pass 78 is a pass that is engraved with a flange portion that is bent or folded inward on the upper and lower rolls.

[0064] In addition, the shape of the flange formed by bending during finish rolling, that is, the shape in which the flange portion is a straight shape or a shape that is bent or folded inward, is set as the second shape.

[0065] Fig.10 The outline of the bending return forming of the flange portion under the K2 pass 78 is shown. Fig.10 (a) is a cross-sectional view schematically showing the state when the raw material (intermediate raw material) after the final rolling pass of the intermediate rolling starts to contact (intermesh) with the K2 groove. Fig.10 (b) is a cross-sectional view showing the state where the forming is completed with the K2 pass (when the bending forming is completed). In this bending return forming, the web portion 11, flange portion 12, and arm portion 13 of the raw material (intermediate raw material) contact the roller (pass) and undergo bending return forming, but it is preferred to engrave the pass in a manner that avoids the joint portion 14 from contacting the roller (pass) and deforming. The bending forming of the claw portion of the joint portion is performed by the K1 pass 79. It should be noted that the number of rolling passes under the K2 pass 78 and the K1 pass 79 is basically 1 pass.

[0066] In the first rolling pass of the finishing rolling, as described above, the flange portion is bent and returned to form. However, in order to prevent the raw material formed by intermediate rolling from deviating in the up and down directions or left and right directions and causing non-steady-state length changes at the front or rear end, the flange portion can be bent and returned stably, and it is more preferable to use a web guide 60 for rolling on the feed side.

[0067] The web guide 60 used is preferably set to a shape in which the width B of the upper surface 601 of the web guide corresponds to the width B3 of the lower surface of the web after the intermediate rolling is completed and is equal to or slightly narrower than the width B3 of the lower surface of the web, and the angle θ formed by the upper surface 601 of the web guide and the side surface 602 of the web guide is equal to θ3 of the pass K3 at the end of the intermediate rolling (the angle formed by the joint of the web portion 11 and the flange portion 12). It should be noted that in the web guide in which the width B of the upper surface 601 of the web guide is set to be equal to the width B3 of the lower surface of the web, scratches may occur on the inner surface of the flange or the lower surface of the web, so usually, B is preferably narrower than B3 by about 2mm to 8mm. Fig.11 (a) shows the preferred shape of the web guide. It should be noted that, Fig.11 (b) shows the arrangement position of the web guide 60 .

[0068] By using the web guide 60 as described above on the rolling feed side of the first rolling pass of the finishing rolling, the web lower surface of the raw material formed by the intermediate rolling and the joint between the web portion and the flange portion can be fully maintained and guided to the K2 die 78. As a result, the deviation of the raw material in the vertical direction and the horizontal direction can be prevented, and the bending return forming of the flange portion can be stably performed.

[0069] The bending forming of the claw portion of the joint portion 14 is performed by the K1 hole type 79 as the final hole type. However, if only this hole type is used, there is a case where the claw bending amount becomes too large and appropriate claw bending forming cannot be performed. In such a case, it is preferable to perform claw bending preforming of the joint portion. The claw bending preforming of the joint portion is preferably performed by providing a claw bending roller such as that described in Japanese Patent Publication No. 2006-272343 on the delivery side (rear surface) of the K2 hole type 78.

[0070] Regarding the preforming of bending the claw from the outside to the inside, use Fig.12 The claw bending roller 8 shown in the figure, while the bending part of the arm 13 is restricted by the vertical roller 82 and the vertical part of the arm 13 is restricted by the horizontal rollers 83a and 83b, the claw 7A is bent from the outside to the inside by the vertical roller 81. It should be noted that the vertical roller 81 is arranged in a manner that the central axis is located outside the claw 7A.

[0071] After the claw bending preforming of the joint portion is performed using such a claw bending roller, if claw bending forming is performed using the K1 pass, the claw bending amount using the K1 pass can be optimized.

[0072] It should be noted that, in the above-mentioned embodiment, the flange portion is bent back in the first rolling pass of the finish rolling, but the bending back may be performed step by step through a plurality of rolling passes including the first rolling pass. In this case, in addition to the K2 pass 78, the K1 pass 79 may be used to perform the bending back of the flange, and other pass types may be provided between the K2 pass 78 and the K1 pass 79 for the bending back.

[0073] Hereinafter, the present invention will be further described based on examples.

[0074] Example

[0075] use Figure 2 The rolling equipment group 2 shown in the figure is used to load the raw material (steel slab (steel grade: SYW295)) into the heating device 3, heat it to a heating temperature of 1300°C, and then use the roughing mill 4, the intermediate rolling mill 5, and the finishing mill 6 to carry out rolling to produce a steel sheet with a web wall thickness of 17 mm, a flange wall thickness of 12 mm, an effective height H of 370 mm, and an effective width W of 900 mm. Figure 1 The shape shown is a high hat-shaped steel sheet pile.

[0076] In the rough rolling, the heated raw material (steel raw material) is rolled by the rough rolling mill 4 having upper and lower rolls engraved with the Box pass, K8 pass, and K7 pass, and is shaped into a shape close to the cross-sectional shape of the product. Next, the raw material shaped by the rough rolling is sequentially rolled (intermediate rolling) using the first intermediate rolling mill 5 having upper and lower rolls engraved with the K5 pass and the K4 pass, and the second intermediate rolling mill 5 having upper and lower rolls engraved with the K6 pass and the K3 pass. Specifically, the first rolling pass in the intermediate rolling is carried out in the order of pass K5 and pass K6 (no pressing in K5), the second rolling pass is carried out in the order of pass K6 and pass K5, and then, as the third rolling pass, rolling is carried out in the order of pass K4 and pass K3.

[0077] After the intermediate rolling is completed, the flange portion is bent or folded outward in the first shape. Therefore, if the hole type used in the intermediate rolling is, for example, the K3 hole type, it is set to Figure 7 The hole profile with the shape shown in (a) is a hole profile with a shallow hole profile. It should be noted that the hole profile with a shallow hole profile is also set in the K6 hole profile, the K5 hole profile and the K4 hole profile. In addition, in the intermediate rolling, the hole profile depth H of the hole profile used is changed in the order of the hole profiles passed (the order of the K6 hole profile, the K5 hole profile, the K4 hole profile and the K3 hole profile) in a manner that satisfies the following formula (1).

[0078] H6≤H5≤H4≤H3......(1)

[0079] The depth H of the pass used is a ratio to the product height (reference: 1.0), as shown in Table 1. Steel sheet pile No. 3 is a comparative example in which a pass having a linear flange portion was used in all rolling passes of the intermediate rolling.

[0080] For each roll having a hole profile with the above-mentioned depth H, the stress generated at each part of the roll during rolling was calculated in advance using the finite element method, and the rolling resistance load (unit MN) under each hole profile was calculated in a manner to avoid the stress exceeding the allowable stress of the roll material. The obtained results are recorded in Table 1. Of course, if the hole profile depth H increases, the value of the resistance load decreases, and the risk of roll breakage increases.

[0081] Next, the raw material shaped by the intermediate rolling is subjected to finish rolling to be shaped into a product shape. It should be noted that in the first rolling pass of the finish rolling, the K2 die 78 is used to perform the bending return forming of the flange portion from the shape of the flange portion bent outward to the second shape of the flange portion being linear.

[0082] It should be noted that in a part of the first rolling pass of the finish rolling, the web guide 60 was used for rolling on the rolling feed side. The web guide 60 is set Fig.11 In the shape shown in (a), the width B of the upper surface (upper surface of the web guide) is set to a size approximately equal to the width B3 of the lower surface of the web of the K3 hole type (a size 4 mm narrower than B3), and the angle θ formed by the upper surface of the web guide and the side surface of the web guide is set to be equal to the angle θ3 formed by the joint of the web part and the flange part at the end of the intermediate rolling.

[0083] After the first rolling pass of the finish rolling, the joint portion is claw-bent using the K2 pass 79 to form a hat-shaped steel sheet pile (product). It should be noted that in the examples of the present invention, claw bending rollers are used on the delivery side of the first rolling pass to perform pre-forming of claw bending, and then claw bending is performed.

[0084] The obtained product (steel sheet pile) was measured from the front end of the rolling process to measure the effective width dimension W and height dimension H (refer to Figure 1 (a)), and confirmed the joint shape by visual observation, and measured the above-mentioned dimensions W, H, and the length of the non-steady-state portion (length in the longitudinal direction (m)) of the rolled front and rear ends where the joint shape did not converge within the tolerance range.

[0085] The obtained results are collectively shown in Table 1.

[0086] [Table 1]

[0087]

[0088] In the steel sheet piles No. 1 and No. 2, which are examples of the present invention, rolling was performed until the final pass of the finish rolling, and the product was successfully extracted. In particular, in the steel sheet pile No. 2, the generation of the non-stable part at the front end and the rear end that did not become the product was small due to the effect of the web guide, and a good result was obtained.

[0089] In contrast, in the steel sheet pile No. 3 as a comparative example, the actual rolling load during rolling at the K5 pass was 12.54 MN, which exceeded the roll load resistance of 12.45 MN. Therefore, further rolling was judged to be dangerous, and rolling after the K4 pass was abandoned.

[0090] Thus, according to the present invention, the flange portion can be stably bent back and then the claw can be bent, and a high steel sheet pile can be easily manufactured. In addition, according to the present invention, the depth of the groove engraved on the roll can be reduced, and the reduction in the bending resistance of the roll can also be reduced.

[0091] Description of symbols

[0092] 1Steel sheet pile

[0093] 1A hat-shaped steel sheet pile, 1B U-shaped steel sheet pile

[0094] 2 Rolling equipment group (rolling equipment group for steel sheet pile manufacturing)

[0095] 3 Heating device

[0096] 4 Roughing mill

[0097] 5Intermediate rolling mill

[0098] 6Finishing mill

[0099] 8 claw bending roller

[0100] 11 web part, 12 flange part, 13 arm part, 14 joint part

[0101] 41 upper roller (upper roughing roller), 42 lower roller (lower roughing roller)

[0102] 51 upper roller (upper middle processing roller), 52 lower roller (lower middle processing roller)

[0103] 60 web guide

[0104] 61 upper roller (upper finishing roller), 62 lower roller (lower finishing roller)

[0105] 81 vertical roller, 82 vertical roller, 83 horizontal roller

[0106] 601 is the upper surface of the web guide, 602 is the side surface of the web guide.

Claims

1. A method for manufacturing a steel sheet pile, comprising: using a plurality of pass types, sequentially performing rough rolling, intermediate rolling and finish rolling on a heated raw material to manufacture a steel sheet pile having a flange portion of a predetermined shape, wherein: In the intermediate rolling, a pass having a pass height smaller than a product height is used so that the flange portion is rolled in a manner such that the shape after the intermediate rolling becomes a first shape bent or folded outward. In the finish rolling subsequent to the intermediate rolling, the flange portion of the first shape is bent into a straight shape or a second shape that is bent or folded inward, and the height dimension of the second shape becomes the product height.

2. The method for manufacturing a steel sheet pile according to claim 1, wherein: The rolling pass in which the bending forming is performed in the finish rolling is a rolling pass using a web guide on the rolling feed side.

3. The method for manufacturing a steel sheet pile according to claim 2, wherein: The web guide has, in a cross section perpendicular to the rolling direction, an upper surface width of the web guide that is equal to or narrower than the lower surface width of the raw web after the final rolling pass of the intermediate rolling, and an angle between the upper surface of the web guide and the side surface of the web guide that is equal to the angle formed by the joint between the raw web and the flange after the final rolling pass of the intermediate rolling.

4. The method for producing a steel sheet pile according to any one of claims 1 to 3, wherein In the finish rolling, claw bending is performed in a rolling pass immediately following the rolling pass in which the bending is performed.

5. The method for manufacturing a steel sheet pile according to claim 4, wherein: In the finish rolling, on the delivery side of the rolling pass in which the bending forming is performed, the claw bending is preformed, and then the claw bending is performed.

6. A rolling equipment group for manufacturing steel sheet piles, which is a rolling equipment group for manufacturing steel sheet piles, which is a heating device, a rough rolling mill, an intermediate rolling mill and a finishing rolling mill arranged in sequence, wherein: The rough rolling mill, the intermediate rolling mill, and the finishing rolling mill are rolling mills each having upper and lower rolls with holes engraved thereon. The pass profile of at least a portion of the intermediate rolling mill is a pass profile whose height is smaller than the product height and is engraved in such a manner that the flange portion is in a first shape that is bent or folded outward. The pass of a part of the finishing mill is a pass engraved so as to bend the flange portion of the first shape into a straight shape or a second shape that is bent or folded inward, and the height dimension of the second shape becomes the product height.

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