Hat-shaped steel sheet pile manufacturing equipment and manufacturing method

Abstract

To manufacture a large-sized product such as a hat-shaped steel sheet pile with high efficiency by bend-molding a rolled material after hot finish rolling while reducing bend-molding torque.SOLUTION: A facility for manufacturing a hat-shaped steel sheet pile includes a rough rolling mill, an intermediate rolling mill, a finish rolling mill and a bend-molding machine. The bend-molding machine is constituted of multiple stands including at least two or more stands for performing molding of changing an angle defined by a flange corresponding part and a web corresponding part by changing a flange inclination angle of a rolled material with an upper- and lower-hole type roller and changing an angle defined by the flange corresponding part and an arm corresponding part. A relationship between an inter-stand distance L(m) between two stands of the multiple stands disposed tandem while being adjacent to each other and a width length B(mm) of the flange corresponding part of the rolled material meets a following expression (1): 4.4≤L / (B / 1000) ... (1).SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a manufacturing facility and a manufacturing method for a hat-type steel sheet pile. [Background technology]

[0002] In the manufacture of hat-shaped steel sheet piles having joints at both ends, a typical process involves first heating a rectangular material to a predetermined temperature in a heating furnace and rolling it sequentially using a roughing mill, an intermediate mill, and a finishing mill equipped with grooves. For example, Patent Document 1 discloses a method for manufacturing hat-shaped steel sheet piles by forming multiple grooves on rolls during roughing, intermediate, and finishing. However, when manufacturing large, asymmetric products such as hat-shaped steel sheet piles, manufacturing them using the roughing, intermediate, and finishing mills requires multiple grooves, which requires large-scale equipment. Furthermore, the manufacturing method becomes complicated, making it more likely that the product will have shape variations or defects. Furthermore, manufacturing steel sheet piles with large widths and heights and different shapes requires large-scale equipment and multiple rolls.

[0003] In view of the above-mentioned circumstances, for example, Patent Document 2 discloses a technology in which steel sheet piles are rolled and manufactured by hot rolling, and then bent (hereinafter also referred to as bending forming) by cold processing using roll forming with a large number of multi-stage support rolls, thereby manufacturing steel sheet piles with a width that exceeds that of rolling equipment and steel sheet piles with a high cross-sectional height.

[0004] Furthermore, for example, Patent Document 3 discloses a method for manufacturing a steel sheet pile in which rough rolling, intermediate rolling, and finish rolling are performed by hot rolling, and then bending is performed using upper and lower grooved rolls in the hot state to bend the corners of the rolled material. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-88176 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-230916 [Patent Document 3] Japanese Patent Publication No. 2021-142564 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, various manufacturing methods for hat-shaped steel sheet piles have been devised, but the reality is that these manufacturing methods do not take into consideration reducing the torque of equipment such as rolling mills and forming machines. For example, in the case of Patent Document 1, as the height of the product increases, the roll diameter of the rolling mill must also be increased. The increase in height and roll diameter synergistically increases the torque, making it impossible to manufacture using existing rolling equipment. Furthermore, Patent Document 2 discloses bending using support rolls, but the support rolls are flat rolls that do not directly press the corners of the rolled material, so multiple rolls are required and the processing load on each roll is large, and therefore a reduction in the forming torque is required.

[0007] Furthermore, in the manufacturing method exemplified in Patent Document 2, bending is performed by cold working, and furthermore, because the corners of the rolled material are not directly pressed using support rolls, which are flat rolls, there are problems such as the corners being difficult to directly plastically deform, making it difficult to perform effective bending, and the cold working method also makes it easy for springback after forming to become large.Furthermore, when the web and flange are formed at different times using multiple forming rolls (support rolls), there is also the problem that the fulcrum is shifted in the longitudinal direction of the rolled material, reducing the efficiency of bending.

[0008] Furthermore, the above-mentioned Patent Document 3 discloses a manufacturing technology for steel sheet piles by hot bending, and describes that bending is performed using, for example, a bending machine consisting of two stands. However, when bending is performed using a bending machine consisting of multiple stands, the influence of the distance between stands on the forming torque of each stand (especially the rear stands) is not mentioned or even suggested.

[0009] In view of the above circumstances, an object of the present invention is to provide a manufacturing facility and a manufacturing method for hat-shaped steel sheet piles that can reduce the bending torque when manufacturing large products such as hat-shaped steel sheet piles with high efficiency by bending the rolled material after hot finish rolling. [Means for solving the problem]

[0010] In order to achieve the above object, according to the present invention, there is provided a manufacturing facility for a hat-type steel sheet pile, which is equipped with a roughing mill, an intermediate rolling mill, a finishing rolling mill, and a bending machine, and the bending machine is configured to change the angle between the flange corresponding portion and the web corresponding portion by changing the flange inclination angle of the rolled material using upper and lower grooved rolls, and to change the angle between the flange corresponding portion and the arm corresponding portion. The bending machine is configured to change the angle between the flange corresponding portion and the arm corresponding portion by changing the flange inclination angle of the rolled material using upper and lower grooved rolls, and to change the angle between the flange corresponding portion and the arm corresponding portion. The bending in the bending machine is performed by configuring the roll gap of the bending machine to be larger than the thickness of the flange corresponding portion and the web corresponding portion of the rolled material after finish rolling, and by bringing at least the inside of the corner portion, which is the connecting portion between the web corresponding portion and the flange corresponding portion, and the predetermined location of the inside of the corner portion, which is the connecting portion between the flange corresponding portion and the arm corresponding portion, into contact with the upper and lower grooved rolls in a hot state; A manufacturing facility for hat-type steel sheet piles is provided, characterized in that the relationship between the stand distance L (m) of two adjacent tandem-arranged stands among the plurality of stands and the width length B (mm) of the flange-corresponding portion of the rolled material satisfies the following formula (1): 4.4≦L / (B / 1000) (1)

[0011] The relationship between the distance L (m) between two adjacent stands among the plurality of stands and the width B (mm) of the flange corresponding portion of the rolled material may satisfy the following formula (4). 5.5≦L / (B / 1000)≦10 (4)

[0013] In the case of a plurality of stands constituting the bending machine, only one of the upper and lower slotted rolls of each stand may be driven.

[0014] The bending machine and the finishing mill may be arranged in tandem.

[0015] The flange width of the hat-shaped steel sheet pile may be 377 (mm) or more.

[0016] According to another aspect of the present invention, there is provided a manufacturing method for manufacturing hat-shaped steel sheet piles in the above-described manufacturing equipment for hat-shaped steel sheet piles, characterized in that when hat-shaped steel sheet piles of multiple sizes are manufactured using the same bending machine, the stand-to-stand distance L is determined so as to satisfy the formula (1) or (4) when the flange width B of the multiple sizes is the largest. [Effects of the Invention]

[0017] According to the present invention, there is provided a manufacturing facility and a manufacturing method for hat-shaped steel sheet piles that can reduce the bending torque when manufacturing large products such as hat-shaped steel sheet piles with high efficiency by bending the rolled material after hot finishing rolling. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic explanatory diagram of a rolling line according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic side cross-sectional view of a bending machine. [Figure 3] FIG. 2 is a schematic front view of the bending machine. [Figure 4] FIG. 4 is a schematic enlarged front view showing the groove shape of the first stand. [Figure 5] FIG. 10 is a schematic enlarged front view showing the groove shape of the second stand. [Figure 6]1A and 1B are explanatory diagrams illustrating the shape change of the rolled material as it is bent in the first stand and the second stand, where (a) shows a schematic cross-sectional view before processing in the first stand, (b) shows a schematic cross-sectional view during processing in the first stand, and (c) shows a schematic cross-sectional view during processing in the second stand. [Figure 7] FIG. 10 is an explanatory diagram of contact points of a finishing material in a bending machine. [Figure 8] FIG. 10 is an explanatory diagram regarding the definition of a flange width. [Figure 9] 1 is a graph showing the relationship between the distance between stands and the forming torque when bending is performed independently in two stands and when bending is performed in tandem. [Figure 10] 1 is a graph showing the relationship between L / (B / 1000) and the torque ratio in the second stand when bending is performed using a bending machine configured with two stands. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this specification and the drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted. In this embodiment, a case where a hat-shaped steel sheet pile is manufactured as a steel sheet pile product will be described.

[0020] <Rolling line configuration> FIG. 1 is an explanatory diagram of a rolling line T (indicated by a dashed line in the figure) for manufacturing a hat-shaped steel sheet pile according to an embodiment of the present invention, and rolling mills and the like provided on the rolling line T. In FIG. 1, the rolling direction of the rolling line T is indicated by an arrow, and the material to be rolled flows in this direction. Then, rolling and bending are performed in each rolling mill and bending machine on the rolling line T, and a product is formed. In FIG. 1, a rolling method in which the material to be rolled is made to reciprocate multiple times in the same rolling mill (so-called multi-pass rolling) is also shown by a dashed line.

[0021] As shown in Fig. 1, in the rolling line T, a roughing mill 10, a first intermediate rolling mill 13, a second intermediate rolling mill 16, a finishing mill 19, and a bending mill 20 are arranged in this order from the upstream side. In addition, an edger rolling mill 14 is arranged adjacent to the upstream side of the first intermediate rolling mill 13, and an edger rolling mill 17 is arranged adjacent to the downstream side of the second intermediate rolling mill 16.

[0022] In the rolling line T, rectangular materials (materials to be rolled) heated in a heating furnace (not shown) are hot rolled in succession in the roughing mill 10 to the finishing mill 19, and are further hot shaped by the bending machine 20 to become final products. For the sake of explanation, the material to be rolled rolled by the roughing mill 10 will be referred to as a rough material, the material to be rolled by the first intermediate rolling mill 13 to the second intermediate rolling mill 16 will be referred to as an intermediate material, and the material to be rolled by the finishing mill 19 will be referred to as a finished material 19a. That is, the finished material 19a is shaped (cross-section changed) by the bending machine 20 to become a final product (i.e., a hat-shaped steel sheet pile product).

[0023] Here, the roughing mill 10, the first intermediate rolling mill 13, the second intermediate rolling mill 16, the finishing rolling mill 19 arranged in the rolling line T, and the associated edger rolling mills 14 and 17 are common equipment that has been used conventionally in the manufacture of steel sheet piles, and therefore detailed explanations of the device configuration, etc. will be omitted in this specification.

[0024] <Configuration of bending machine> Next, the detailed configuration of the bending machine 20 will be described with reference to the drawings. Fig. 2 is a schematic side cross-sectional view of the bending machine 20, and Fig. 3 is a schematic front view of the bending machine 20. The bending machine 20 shown in Figs. 2 and 3 bends a finished material 19a that has been finish-rolled in a finishing mill 19. Fig. 3 also shows a schematic front view of a first stand 22 provided in the bending machine 20, which will be described below. Here, in this embodiment, the bending machine 20 is described as being composed of two forming stands (forming stands 22 and 23, which will be described below), but the bending machine 20 may be composed of any number of stands.

[0025] As shown in Fig. 2, the bending machine 20 according to this embodiment has two forming stands 22, 23 (hereinafter also referred to as the first stand 22 on the upstream side and the second stand 23 on the downstream side) arranged adjacent to each other in tandem. In this case, the distance between the centers of the two forming stands 22, 23 is taken as the stand distance L. Also, as shown in Fig. 3, each of the stands 22, 23 is provided with a forming groove (groove dies 45, 55 described below) consisting of an upper groove roll and a lower groove roll, and the groove shapes of the first stand 22 and the second stand 23 are different.

[0026] Here, the roll configuration and caliber shape of the first stand 22 and the second stand 23 will be described. Fig. 4 is a schematic enlarged front view showing the caliber shape of the first stand 22, and Fig. 5 is a schematic enlarged front view showing the caliber shape of the second stand 23. Note that Fig. 4 shows, by a dashed dotted line, the cross-sectional shape of the finished material 19a in the state before being formed by the bending machine 20, and Fig. 5 shows, by a dashed dotted line, the cross-sectional shape of the finished material 19a' in the state before being formed by the second stand 23. In the following, an example will be described in which a rolled material having a substantially hat shape is bent in an upward-open position (with the web corresponding portion described below positioned downward and the arm corresponding portion positioned upward).

[0027] 3 and 4, the first stand 22 is provided with an upper perforated roll 40 and a lower perforated roll 41 supported by a housing 44, and the upper perforated roll 40 and the lower perforated roll 41 form a perforated roll 45. The perforated roll 45 has a shape just short of a hat-shaped steel sheet pile product (i.e., a shape similar to a hat-shaped steel sheet pile product) from the part corresponding to the flange to the part corresponding to the joint. The perforated roll 45 changes the angle formed between the part corresponding to the flange of the finishing material 19a (i.e., the flange-corresponding part) and the part corresponding to the web of the finishing material 19a (i.e., the web-corresponding part), and the angle formed between the part corresponding to the arm of the finishing material 19a (i.e., the arm-corresponding part), respectively, and bends and shapes the height and width of the finishing material 19a into a predetermined shape (i.e., a cross-sectional shape similar to that of the product). In particular, when manufacturing a hat-shaped steel sheet pile, a method is adopted in which the material to be rolled (raw material to finished material 19a) is rolled in a shape with a low height in the roughing mill 10 to the finishing mill 19, and the material to be rolled is bent in the bending machine 20 so as to increase the height of the material to a desired product height. This makes it possible to manufacture a large-sized hat-shaped steel sheet pile product.

[0028] 5, the second stand 23 has an upper perforated roll 50 and a lower perforated roll 51 supported by a housing 54, and the upper perforated roll 50 and the lower perforated roll 51 form a groove 55. This groove 55 has a shape close to the desired product shape, and changes the angle between the part corresponding to the flange formed in the first stand 22 of the bending machine 20 (i.e., the flange corresponding part) and the part corresponding to the web of the finishing material 19a (i.e., the web corresponding part), and the angle between the part corresponding to the arm (i.e., the arm corresponding part), respectively, to form the flange shape, arm shape, and joint shape into a predetermined shape (i.e., the product shape). That is, in this second stand 23, the inclination angle of the flange corresponding part, which was insufficient for the product shape in the forming in the first stand 22, is changed to an angle corresponding to the product shape.

[0029] Here, the roll gaps in the grooved dies 45 and grooved dies 55 during bending (the roll gap between the upper grooved roll 40 and the lower grooved roll 41 and the roll gap between the upper grooved roll 50 and the lower grooved roll 51) are configured to be larger than the thickness of the flange-corresponding portion and the web-corresponding portion of the finishing material 19a. That is, in the bending machine 20, the thickness of the finishing material 19a is not reduced, and the grooved rolls of the first stand 22 and the second stand 23 and the finishing material 19a come into contact only at certain predetermined locations described below to perform bending.

[0030] In this specification, "contact" refers to a state in which only one of the upper and lower surfaces of a specific portion of the finishing material 19a abuts against the peripheral surface of the grooved roll in the bending machine 20. In contrast, "rolling down" refers to a state in which both the upper and lower surfaces of a specific portion of the finishing material 19a abut against the grooved roll in the bending machine 20, and a force is applied to reduce the thickness.

[0031] For example, the roll gap at the portions facing the web and flange portions is preferably about 0.5 mm to 3 mm larger than the thickness of the flange and web portions of the finishing material 19a. Additionally, the roll gap at the locations of the grooves 45 and 55 that correspond to the arm portions of the finishing material 19a may be configured to be larger than the thickness of the arm portions over the entire cross section. If the roll gap allowance range is smaller than 0.5 mm, the thickness of the finishing material 19a may be reduced due to variations in thickness, increasing the load on the bending machine 20. If the allowance range is larger than 3 mm, the inclination angle of the flange portions may not be adjusted to the target angle.

[0032] <Bending> Next, we will explain the shaping of the rolled material in the above-mentioned stands 22 and 23. Figure 6 is an explanatory diagram of the shape change of the rolled material (finished material 19a) that is bent in the first stand 22 and the second stand 23, where (a) shows a schematic cross-sectional view before processing in the first stand 22, (b) shows processing in the first stand 22, and (c) shows processing in the second stand 23. 6(a), the finishing material 19a has a generally hat-shaped configuration and is composed of a generally horizontal web corresponding portion 60, flange corresponding portions 62, 63 connected to both ends of the web corresponding portion 60 by corner portions 70 (hereinafter also referred to as web-flange corner portions 70) at a predetermined angle (shown as angle α in the figure) larger than the product shape, arm corresponding portions 65, 66 connected to the ends of each flange corresponding portion 62, 63 different from the connection side with the web corresponding portion via corner portions 71 (hereinafter also referred to as flange-arm corner portions 71), and joint corresponding portions 68, 69 formed at the tips of the arm corresponding portions 65, 66. Furthermore, the thickness of the finishing material 19a is approximately the thickness of the product due to rolling in the finishing rolling mill 19, and the shape of the joint corresponding portions 68, 69 is also approximately the shape of the joint of the product.

[0033] The finishing material 19a shown in Figure 6(a) is bent in the hole 45 of the first stand 22 so that the angle α between the web corresponding portion 60 and the flange corresponding portions 62, 63 becomes small (becoming the angle α1 shown in Figure 6(b)), and the finishing material 19a reaches the desired height as shown in Figure 6(b). That is, in the first stand 22, bending is performed so that the height of the finishing material 19a becomes large.

[0034] Next, as shown in Figure 6(c), in the hole mold 55 of the second stand 23, the finishing material 19a is bent so that the angle α1 between the web corresponding portion 60 and the flange corresponding portions 62, 63 becomes smaller (becomes the angle α2 shown in Figure 6(c)), and the finishing material 19a is bent into approximately the product shape.

[0035] FIG. 7 is an explanatory diagram of contact points of the finishing material 19a in the bending machine 20, with (a) to (d) each showing an example of the contact points. In FIG. 7, the contact points are indicated by bold lines. In the grooved rolls 45 of the first stand 22 and the grooved rolls 55 of the second stand 23, the grooved rolls and the finishing material 19a contact only at certain predetermined locations, and no reduction in thickness is performed. Specific contact points between the grooved rolls and the finishing material 19a are, for example, the inside corners 70a and 70b at the boundaries between the web-corresponding portions 60 and the flange-corresponding portions 62 and 63, and the inside corners 71a and 71b at the boundaries between the flange-corresponding portions 62 and 63 and the arm-corresponding portions 65 and 66, as shown in FIG. 7(a). Here, "contact" refers to at least contact between the material and the grooved rolls, and may also refer to a state in which a force pressing the material is applied.

[0036] As shown in Figure 7(a), contact points 70a and 70b are located inside corner 70, which is the boundary between web-corresponding portion 60 and flange-corresponding portions 62 and 63. On the other hand, contact points 71a and 71b are located inside corner 71, which is the boundary between flange-corresponding portions 62 and 63 and arm-corresponding portions 65 and 66. At contact points 71a and 71b, reaction forces are generated in directions that balance the reaction forces at 70a and 70b, respectively. This allows corner portions 70 and 71 to undergo plastic deformation.

[0037] Here, by bringing the central portion 60a of the underside (outside) of the web corresponding portion 60 shown in Figure 7(b) into contact with the opposing pre-perforated rolls 41, 51, bending of the corners formed by the flange corresponding portions 62, 63 and the web corresponding portion 60 can be carried out efficiently. During bending, the web corresponding portion 60 tends to warp downward in the figure, so by bringing the pre-perforated rolls into contact with the central portion 60a of the underside away from both sides (corner portions 70) of the web corresponding portion 60, a bending moment can be effectively applied to both ends of the web corresponding portion 60. Furthermore, at least in the second stand 23, which is the final stand, the upper surfaces (outside surfaces) 65a, 66a of the arm corresponding portions 65, 66 become the contact points in order to make the arm corresponding portions 65, 66 approximately horizontal.

[0038] In addition, by appropriately setting the allowance value of the roll gap as described above, as shown in Fig. 7(c), in the groove 45 of the first stand 22 and the groove 55 of the second stand 23, it is desirable that the inner upper parts 62a, 63a of the flange corresponding parts 62, 63 of the finishing material 19a contact the upper grooved rolls 40, 50, and the outer lower parts 62b, 63b of the flange corresponding parts 62, 63 contact the lower grooved rolls 41, 51. By contacting the points shown in Fig. 7(c), three-point bending is generated at the corner parts 70, 71 due to the grooved roll shape, so that the corner parts 70, 71 can be sufficiently plastically deformed, and highly accurate bending can be performed.

[0039] 7(d), in addition to the locations described in Figures 7(a) to 7(c), the upper surfaces (outer surfaces) 68a, 69a of the joint corresponding portions 68, 69 may be brought into contact with the upper perforated rolls 40, 50. By bringing the locations shown in Figure 7(d) into contact, the joint corresponding portions 68, 69 can also be formed to be approximately horizontal, enabling bending with even higher precision.

[0040] While preferred contact points for the finishing material 19a during bending have been described with reference to Figures 7(a) to (d), as shown in Figure 7, the contact points during bending are not positioned to reduce the thickness of the finishing material 19a. Specifically, the configuration is such that a specific point of the finishing material 19a is not pressed from both sides by both the upper and lower perforated rolls (i.e., reduced), and the roll gap between the upper and lower perforated rolls is configured to be larger than the thickness of the finishing material 19a, so the thickness is not reduced. If the web corresponding portion 60 and the flange corresponding portions 62, 63 are not reduced, there is no need to unnecessarily increase the reduction reaction force.

[0041] 7 illustrates an example of a configuration in which a portion of each grooved roll contacts each corner portion 70, 71, but the contact points of each grooved roll in the present invention are not limited to this. That is, in addition to the contact points described above with reference to FIG. 7, further contact points may be provided.

[0042] <Bending torque> Here, the inventors focused on the bending torque of the bending machine 20 described above and conducted detailed research into the fact that the bending torque (hereinafter also simply referred to as the forming torque) required by the bending machine 20 tends to increase as the cross-sectional dimension of the rolled material (finish material 19a) and the amount of bending increase. In particular, when bending is performed using multiple stands (e.g., first stand 22 and second stand 23) arranged in tandem, as in the bending machine 20 of this embodiment, the inventors discovered that there is a correlation between the forming torque and the distance between the multiple stands and the width of the flange-corresponding portions 62, 63 of the rolled material (hereinafter also simply referred to as the flange width B). This finding will be explained below with reference to graphs and the like (obtained by numerical analysis).

[0043] In this specification, the term "flange width" refers to the width of the flange corresponding portions 62, 63 of the rolled material (finish material 19a) and the length along the flange corresponding portions 62, 63. Specifically, as shown in FIG. 8, on a line (dashed line in FIG. 8) passing through the thickness centers of the web corresponding portion 60, the flange corresponding portions 62, 63, and the arm corresponding portions 65, 66, the straight-line distance between the intersection P1 of the flange corresponding portions 62, 63 with the web corresponding portion 60 and the intersection P2 of the flange corresponding portions 62, 63 with the arm corresponding portions 65, 66 is defined as the flange width B. This length is approximately the same as the flange width length of the final product, and therefore may be defined as the flange width length of the final product.

[0044] Fig. 9 is a graph showing the relationship between the stand distance L and the forming torque when a hat-shaped steel sheet pile of one cross-sectional dimension is bent singly (non-tandem) and in tandem in two stands (first stand 22 and second stand 23) of the bending machine 20 according to this embodiment. The vertical axis of the graph in Fig. 9 represents "tandem torque / single torque" and the horizontal axis represents "stand distance L (m)."

[0045] As shown in Fig. 9, at the first stand 22, the value of "tandem torque / single torque" is almost constant regardless of the stand-to-stand distance L. On the other hand, at the second stand 23, the increase becomes more pronounced as the stand-to-stand distance L becomes smaller, and the torque tends to decrease as the stand-to-stand distance L becomes larger. As the stand-to-stand distance L increases, the torque converges to the single torque.

[0046] The shorter the inter-stand distance L, the greater the forming torque of the rear stand. This is because the rolled material undergoes rapid bending between the stands, and bending is performed while the deformation of the rolled material is constrained by the front stand. When bending is performed by the second stand alone, if the inter-stand distance L is made larger than the distance between the position where the flange angle begins to increase and directly below the roll, it was found that the torque of the rear stand when bending in tandem becomes approximately equal to the torque when bending is performed by the second stand alone.

[0047] Therefore, further studies were conducted on hat-shaped steel sheet piles with different cross-sectional dimensions. Here, for example, when the forming torque of the rear stand (second stand 23) becomes an issue, it may be possible to increase the bending angle of the front stand (first stand 22) and decrease the bending angle of the rear stand to suppress the forming torque of the rear stand. However, in this case, the forming torque of the front stand becomes excessive. Therefore, the inventors studied conditions under which the distribution of bending angles and the inter-stand distance L are optimized to balance the forming torque of the front stand and the rear stand.

[0048] Even in the case of hat-shaped steel sheet piles with different cross-sectional dimensions, the same relationship as above can be obtained between the inter-stand distance L and the forming torque of the rear stand. In other words, it has become clear that when there is no restraint from the front stand, the distance between the position where the flange angle begins to increase and directly below the roll is roughly proportional to the flange width B. Therefore, it is thought that the increase in forming torque of the rear stand depends on the flange width B of the rolled material and the inter-stand distance L.

[0049] The load also shows a similar tendency to the forming torque described above with reference to Fig. 9, and in the first stand 22, the value of "tandem load / single load" is almost constant regardless of the inter-stand distance L. On the other hand, in the second stand 23, the increase becomes more pronounced as the inter-stand distance L becomes smaller, and the load tends to decrease as the inter-stand distance L becomes larger.

[0050] <Relationship between forming torque and stand distance> As described above, the inventors have considered that the forming torque in the rear stand of a two-stand bending machine 20 tends to depend on the flange width B of the rolled material and the stand-to-stand distance L, and have defined the ratio "L / B" of the stand-to-stand distance L to the flange width B as an evaluation index, and have conducted further research into the optimal relationship and optimal conditions between the stand-to-stand distance L and the flange width B of the rolled material based on the relationship between the value L / B and the forming torque.

[0051] The inventors defined the minimum value of the forming torque of the rear stand (here, the second stand 23) as 1, defined the torque increase ratio (hereinafter also referred to as the torque ratio) relative to that minimum torque value as a dimensionless value, and graphed the relationship between the torque ratio and L / (B / 1000). FIG. 10 is a graph showing the relationship between L / (B / 1000) and the torque ratio of the rear stand, the second stand 23, when bending is performed using a bending machine 20 consisting of two stands. Note that the graph in FIG. 10 shows multiple conditions, including conditions with different flange widths B and conditions with different bending angle distributions between the first stand and the second stand. Here, the bending angle at each stand was defined as the difference in the angle of the grooved rolls of the finishing mill 19 and the bending machine 20 corresponding to the angles α, α1, and α2 formed between the web corresponding portion 60 and the flange corresponding portions 62 and 63 shown in FIG. 6.

[0052] As shown in FIG. 10, regardless of whether the flange width B is 377 mm to 657 mm or the bending angle distribution, the torque ratio tends to increase rapidly as the L / (B / 1000) value decreases. In particular, the torque ratio increases rapidly when the L / (B / 1000) value is less than 4.4. Therefore, a significant increase in the motor capacity as the equipment driving force is required to ensure the necessary forming torque, resulting in increased equipment costs and power consumption. To prevent a significant increase in equipment costs and power consumption due to a significant increase in the torque ratio with a decrease in L / (B / 1000), it is preferable to keep the torque ratio at, for example, 1.4 or less. A torque ratio of less than 1.5 relative to the minimum torque is within an acceptable range in terms of equipment costs and power consumption. As shown in FIG. 10, when the torque ratio is kept at 1.4 or less, the L / (B / 1000) value in the bending machine 20 satisfies the following formula (1): 4.4≦L / (B / 1000) (1)

[0053] Furthermore, from the viewpoint of further reducing equipment costs and power consumption in bending, it is preferable to keep the torque ratio value at, for example, 1.2 or less. As can be seen from Fig. 10, when the torque ratio is kept at 1.2 or less, the value of L / (B / 1000) in the bending machine 20 satisfies the following formula (2). 5.5≦L / (B / 1000) (2)

[0054] On the other hand, as shown in Figure 10, even if the inter-stand distance L is increased and the value of L / (B / 1000) is increased, the torque of the rear stand does not decrease below a predetermined value (see Figure 9), so the torque ratio remains at 1. Increasing the inter-stand distance L requires larger guide equipment to guide the rolled material between the stands, which raises concerns about increased equipment costs. It may also impair the stability of the material passing through the stands. For these reasons, it is not advisable to increase the inter-stand distance L more than necessary. As shown in Figure 10, when the value of L / (B / 1000) is 7.0 or greater, the torque ratio approaches 1. Furthermore, as the torque ratio approaches 10, the torque of the rear stand reaches its minimum value, and the torque ratio becomes 1. Therefore, it is desirable to satisfy the following equation (3): L / (B / 1000)≦10 (3) That is, based on the above formulas (2) and (3), a suitable numerical range for L / (B / 1000) can be defined by the following formula (4). 5.5≦L / (B / 1000)≦10 (4)

[0055] The findings described above with reference to Figures 9 and 10 apply to cases where the flange width B is 377 mm, 482 mm, 542 mm, and 657 mm. When hat-type steel sheet pile products with a flange width of less than 377 mm are manufactured using the equipment and method according to this embodiment, the bending torque itself is small, so the impact of an increase in the bending torque on the equipment is small. For example, in the example described below, when the flange width B is 542 mm, the torque of the rear stand is 12.6 tf·m to 21.7 tf·m, whereas when the flange width is less than 377 mm, the torque of the rear stand is about half that. In other words, the technology of the present invention can be effectively applied to the manufacturing of hat-type steel sheet piles with a flange width of 377 mm or more. Furthermore, when manufacturing hat-type steel sheet piles with a flange width of 500 mm or more, the forming torque is large, and the increase in the forming torque significantly affects the equipment, so the application of the technology of the present invention is particularly effective.

[0056] <Action and effect> Based on the findings described above with reference to Figures 9 and 10, in manufacturing hat-shaped steel sheet piles using a bending machine 20 consisting of two stands that satisfies the conditions defined by the above formula (1) or (4), the bending torque of the second stand 23, which is the rear stand, can be minimized. Furthermore, since the same trend as the torque is observed for the load, the load of the second stand 23, which is the rear stand, can also be reduced. This minimizes the motor capacity as the equipment driving force and makes it possible to reduce the size of the motor and auxiliary equipment, thereby reducing equipment costs, saving space, and suppressing power consumption.

[0057] That is, by performing hot bending on the rolled material after hot finish rolling, it is possible to improve the efficiency of the equipment and productivity when manufacturing large products such as hat-shaped steel sheet piles. Note that "hot" here refers to the temperature before the transformation of the rolled material is completed after hot rolling.

[0058] Furthermore, when hat-shaped steel sheet piles of multiple sizes are manufactured using the same bending machine, by determining the stand-to-stand distance L so as to satisfy the above formula (1) or (4) based on the maximum flange width B of the product to be manufactured, it becomes possible to manufacture hat-shaped steel sheet piles of multiple sizes with a forming torque that falls within the equipment specifications of the same bending machine.

[0059] As described above, bending is performed in a hot state. It is also preferable to arrange the finishing rolling mill 19 and the bending machine 20 in tandem and perform the finish rolling and bending continuously in a hot state. Here, hot finish rolling and bending refers to rolling and bending at a temperature before the transformation of the rolled material is complete. Even if the inter-stand distance L of the bending machine 20 is set to a predetermined distance and the forming torque of the rear stand is minimized, the temperature may drop in the cropped portion (unsteady portion) at the tip of the rolled material, which may cause misalignment and jamming. Therefore, the forming torque tends to increase instantaneously when the material is jammed compared to the steady portion. Therefore, by arranging the finishing rolling mill 19 and the bending machine 20 in tandem, the finishing rolling mill 19 can effectively push the rolled material into the bending machine 20, thereby reducing the forming torque when the material is jammed.

[0060] While one embodiment of the present invention has been described above, the present invention is not limited to the illustrated embodiment. It is clear that a person skilled in the art can conceive of various modifications and alterations within the scope of the ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

[0061] In the above embodiment, the bending machine 20 is illustrated and described as being composed of a first stand 22 and a second stand 23, but the scope of application of the present invention is not limited to this. For example, the bending machine 20 may be composed of any number of multiple stands, such as three or more. When the bending machine 20 is composed of multiple stands, bending can be shared among the stands. When the bending machine 20 is composed of multiple stands, the effects of the present invention can be achieved by satisfying each of the conditions (conditions defined by formula (1) or formula (4)) described in the above embodiment for each of two adjacent stands.

[0062] The number of stands is determined based on a balance between the bending angle and capital investment. For example, if the total bending angle is approximately 20° to 40°, the two-stand configuration described in the above embodiment is suitable. The total bending angle is determined by the relationship between the inclination angle of the flange-corresponding portion during rolling, which is regulated by conditions such as the roll diameter of the rolling mill, and the inclination angle of the flange portion of the product. Therefore, as the flange width increases, the inclination angle of the flange-corresponding portion during rolling decreases, and the total required bending angle tends to increase. While it is generally preferable to equalize the torque of each stand based on motor capacity, the bending angle at the first stand 22 is also subject to constraints such as meshing stability. Therefore, it is preferable to determine the distribution of bending angles between the first stand 22 and the second stand 23 taking these factors into consideration. The bending angles listed in the above embodiment were selected in this manner, but are not limited to this.

[0063] In the above embodiment, the upper and lower perforated rolls of the bending machine 20 can also be configured to drive only one of the upper and lower perforated rolls, and not the other. Driving only one of the upper and lower perforated rolls makes it easier to balance the speed of the sheet when bending in tandem with multiple stands. This reduces tension on the rolled material due to imbalances in speed between the stands, stabilizing the sheet and preventing unnecessary deformation of the rolled material. Additionally, the drive mechanisms, such as the motor, spindle, and gears, for driving the rolls can be simplified, resulting in a smaller facility and reduced facility costs. From the perspective of bite stability, it is preferable to drive the roll that increases the inclination angle of the flange-corresponding portion (the lower perforated roll in the case of the forming postures shown in Figures 3 to 5).

[0064] Furthermore, in the above embodiments and their variations, examples have been given of the case where hat-shaped steel sheet pile products are manufactured in an upward-opening position (with the arm corresponding portion above the web corresponding portion), but the present invention can also be applied to the case where they are manufactured in the opposite downward-opening position (with the arm corresponding portion below the web corresponding portion). [Example]

[0065] In the steel sheet pile manufacturing equipment according to the present invention, following hot finish rolling, flange bending was performed using a bending machine consisting of two consecutive stands to manufacture large hat-shaped steel sheet piles with a product width of 1,400 mm and a product height of 501 mm. The flange width B of the rolled material at this time was 542 mm. The first bending angle at the first stand in the bending process was set to 16°, and the second bending angle at the second stand was set to 17°. The stand distance L was changed within a range of 1.8 m to 4.8 m. The torque and torque increase ratio under each of these conditions are shown in Table 1 below.

[0066] [Table 1]

[0067] As shown in Table 1, when the stand-to-stand distance is 1.8 m, which is the condition for the comparative example, L / (B / 1000) is 3.3, which does not satisfy the conditions stipulated by equation (1) or equation (4) above, and the torque of the second stand is 21.7 tf m, resulting in a torque increase ratio of approximately 1.7. In other words, if the minimum torque is used as the standard, a motor with a capacity 1.7 times larger would be required, resulting in a significant increase in power consumption.

[0068] On the other hand, under the conditions of Example 1, where the stand distance is 2.4 m, L / (B / 1000) is 4.4, satisfying the condition defined by the above formula (1). Under these conditions, the torque of the second stand is 17.9 tf m, and the torque increase ratio is suppressed to approximately 1.4. Furthermore, under the conditions of Example 2, where the stand distance is 3.0 m, L / (B / 1000) is 5.5, satisfying the conditions defined by the above formulas (1) and (4). Under these conditions, the torque of the second stand is 15.2 tf m, and the torque increase ratio is suppressed to approximately 1.2. Furthermore, under the conditions of Examples 3 to 5, the torque of the second stand is suppressed to approximately the minimum value. That is, since Examples 1 to 5 satisfy the condition defined by the above formula (1) or (4), the torque of the subsequent stands is suppressed. This allows, for example, the motor capacity of the equipment to be reduced and power consumption to be reduced. [Industrial Applicability]

[0069] The present invention can be applied to a manufacturing facility and a manufacturing method for a hat-type steel sheet pile. [Explanation of symbols]

[0070] 10...Roughing mill 13...First intermediate rolling mill 14...Edger rolling mill 16...Second intermediate rolling mill 17...Edger rolling mill 19...Finishing rolling mill 19a...Finishing material 20...Bending machine 22...1st Stand 23...Second Stand 40...Upper perforated roll 41...Pre-hole type roll 44…Case 45...hole type 50...Upper perforated roll 51...Pre-hole type roll 54...Housing 55…hole type 60...Web Support Department 62, 63...Flange corresponding parts 65, 66...Arm corresponding parts 68, 69...Joint compatible parts 70, 71...Corner section T...Rolling line

Claims

1. A manufacturing facility for hat-type steel sheet piles, comprising a roughing mill, an intermediate rolling mill, a finishing rolling mill, and a bending machine, The bending machine is composed of two or more stands that change the angle between the flange corresponding portion and the web corresponding portion by changing the flange inclination angle of the rolled material using upper and lower grooved rolls, and that change the angle between the flange corresponding portion and the arm corresponding portion; The bending in the bending machine is performed by configuring the roll gap of the bending machine to be larger than the thickness of the flange corresponding portion and the web corresponding portion of the rolled material after finish rolling, and by bringing at least the inside of the corner portion, which is the connecting portion between the web corresponding portion and the flange corresponding portion, and the predetermined location of the inside of the corner portion, which is the connecting portion between the flange corresponding portion and the arm corresponding portion, into contact with the upper and lower grooved rolls in a hot state; A manufacturing facility for hat-type steel sheet piles, characterized in that the relationship between the stand distance L (m) of two stands arranged adjacent to each other in tandem among the plurality of stands and the width length B (mm) of the flange corresponding portion of the rolled material satisfies the following formula (1): 4.4≦L / (B / 1000)...(1)

2. 2. The manufacturing equipment of claim 1, wherein a relationship between a stand distance L (m) between two adjacent stands among the plurality of stands and a width length B (mm) of a flange corresponding portion of the rolled material satisfies the following formula (4): 5.5≦L / (B / 1000)≦10 (4)

3. A manufacturing facility for hat-shaped steel sheet piles as described in claim 1 or 2, characterized in that in the multiple stands that constitute the bending forming machine, only one of the upper and lower hole-type rolls of each stand is driven.

4. A manufacturing facility for hat-shaped steel sheet piles as described in any one of claims 1 to 3, characterized in that the bending machine and the finishing rolling machine are arranged in tandem.

5. A manufacturing facility for hat-shaped steel sheet piles as described in any one of claims 1 to 4, characterized in that the flange width of the hat-shaped steel sheet piles is 377 (mm) or more.

6. A manufacturing method for manufacturing a hat-shaped steel sheet pile in the manufacturing equipment for the hat-shaped steel sheet pile according to any one of claims 1 to 5, comprising: When manufacturing hat-shaped steel sheet piles of multiple sizes using the same bending machine, A method for manufacturing a hat-shaped steel sheet pile, characterized in that the stand-to-stand distance L is determined so as to satisfy the formula (1) or (4) when the flange width B is the largest among the plurality of sizes.

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