JP7765698B2 - Hat-shaped steel sheet pile manufacturing equipment and manufacturing method - Google Patents

Description

The present invention relates to manufacturing equipment and methods for hat-shaped steel sheet piles.

In the manufacture of hat-shaped steel sheet piles with 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 through a roughing mill, an intermediate rolling mill, and a finishing mill equipped with grooves. For example, Patent Document 1 discloses a method for manufacturing hat-shaped steel sheet piles by carving multiple grooves into the 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, necessitating large-scale equipment. This complicates the manufacturing process and increases the likelihood of product shape variations and defects. Furthermore, manufacturing steel sheet piles with large widths and heights and different shapes requires large-scale equipment and multiple rolls.

In light 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) by cold rolling using roll forming with a large number of multi-stage support rolls, to manufacture steel sheet piles with widths and cross-sectional heights that exceed those of rolling equipment.

For example, Patent Document 3 discloses a method for manufacturing steel sheet piles in which rough rolling, intermediate rolling, and finish rolling are performed by hot rolling, and then the corners of the rolled material are bent by hot bending using upper and lower grooved rolls.

Japanese Patent Application Laid-Open No. 2006-88176 Japanese Patent Application Laid-Open No. 2003-230916 Japanese Patent Application Laid-Open No. 2021-142564

As such, various manufacturing methods for hat-shaped steel sheet piles have been devised, but the reality is that these manufacturing technologies 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 mentioned above, as the height of the product increases, the roll diameter of the rolling mill must also be increased, and the torque increases synergistically with the increase in height and roll diameter, making it impossible to manufacture using existing rolling equipment. Furthermore, Patent Document 2 mentioned above discloses bending using support rolls, but these support rolls are flat rolls and do not directly press against the corners of the rolled material, so multiple rolls are required and the processing load on each roll is large, resulting in a need to reduce the forming torque.

In addition, the manufacturing method exemplified in Patent Document 2 uses cold working to perform the bending process, and the support rolls, which are flat rolls, are used to avoid directly pressing on the corners of the rolled material. This makes it difficult to apply plastic deformation directly to the corners, preventing effective bending. Furthermore, the cold working process also results in significant springback after forming. Furthermore, when the web and flange are formed at different times using multiple forming rolls (support rolls), the fulcrums are misaligned in the longitudinal direction of the rolled material, reducing the efficiency of bending.

Furthermore, the above-mentioned Patent Document 3 discloses a manufacturing technology for steel sheet piles using hot bending, and describes, for example, that bending is performed using a bending machine consisting of two stands. However, when bending is performed using a bending machine consisting of multiple stands, there is no mention or even suggestion of the effect that the distance between stands has on the forming torque of each stand (especially the latter stands).

In light of the above circumstances, the object of the present invention is to provide manufacturing equipment 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.

In order to achieve the above object, according to the present invention, there is provided a manufacturing facility for hat-type steel sheet piles, which is equipped with a roughing mill, an intermediate rolling mill, a finishing rolling mill, and a bending machine, wherein the bending machine is composed of two or more multiple 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 changes the angle between the flange corresponding portion and the arm corresponding portion, and the bending in the bending machine is configured so that the roll gap of the bending machine is larger than the thickness of the flange corresponding portion and the web corresponding portion of the rolled material after finish rolling, and the bending is performed by bringing at least the inside of a corner portion that is a connecting portion between the web corresponding portion and the flange corresponding portion and a predetermined location of the inside of the corner portion that is a 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, and the manufacturing facility for hat-type steel sheet piles is characterized in that the relationship between the stand distance L (m) of two stands that are adjacently arranged in tandem among the multiple 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)

The relationship between the stand 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)

In the case of multiple stands that make up the bending machine, only one of the upper and lower slotted rolls of each stand may be driven.

The bending machine and the finishing rolling mill may be arranged in tandem.

The flange width of the hat-shaped steel sheet pile may be 377 mm or more.

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 hat-shaped steel sheet pile manufacturing equipment, characterized in that when hat-shaped steel sheet piles of multiple sizes are manufactured using the same bending machine, the inter-stand distance L is determined so as to satisfy formula (1) or formula (4) for the value when the flange width B is the largest among the multiple sizes.

The present invention provides manufacturing equipment and a manufacturing method for hat-shaped steel sheet piles that can efficiently manufacture large products such as hat-shaped steel sheet piles by bending the rolled material after hot finish rolling, while reducing the bending torque.

1 is a schematic explanatory diagram of a rolling line according to an embodiment of the present invention. FIG. 2 is a schematic side cross-sectional view of a bending machine. FIG. 2 is a schematic front view of the bending machine. FIG. 10 is a schematic enlarged front view showing the groove shape of the first stand. FIG. 10 is a schematic enlarged front view showing the groove shape of the second stand. 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. FIG. 10 is an explanatory diagram of contact points of a finishing material in a bending machine. FIG. 10 is an explanatory diagram regarding the definition of a flange width. 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. 10 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.

Embodiments of the present invention will be described below with reference to the drawings. Note that in this specification and drawings, components having substantially the same functional configuration will be assigned the same reference numerals, and redundant explanations will be omitted. Note that in this embodiment, a case will be described in which hat-shaped steel sheet piles are manufactured as steel sheet pile products.

<Rolling line configuration>
FIG. 1 is an explanatory diagram of a rolling line T (indicated by a dashed line in the drawing) 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 reciprocated multiple times in the same rolling mill (so-called multi-pass rolling) is also shown by a dashed line.

As shown in Figure 1, the rolling line T is arranged, in order from upstream, with 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. Furthermore, 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.

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

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

<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.

As shown in Figure 2, the bending machine 20 of this embodiment has two adjacent forming stands 22, 23 (hereinafter also referred to as the upstream first stand 22 and the downstream second stand 23) arranged in tandem. In this case, the center-to-center distance between the two forming stands 22, 23 is referred to as the stand-to-stand distance L. Also, as shown in Figure 3, each stand 22, 23 is engraved with a forming groove (groove 45, 55 described below) consisting of an upper groove roll and a lower groove roll, and the groove shape differs between the first stand 22 and the second stand 23.

The roll configuration and groove shape of the first stand 22 and the second stand 23 will now be described. Figure 4 is a schematic enlarged front view showing the groove shape of the first stand 22, and Figure 5 is a schematic enlarged front view showing the groove shape of the second stand 23. Note that Figure 4 uses a dashed line to show the cross-sectional shape of the finished material 19a before it is formed by the bending machine 20, and Figure 5 uses a dashed line to show the cross-sectional shape of the finished material 19a' before it is formed by the second stand 23. The following description will be given, as an example, of bending a rolled material having a generally hat-like shape in an upwardly open position (with the web-corresponding portion, described below, positioned downward and the arm-corresponding portion positioned upward).

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 shape of this perforated roll 45 from the portion corresponding to the flange to the portion corresponding to the joint is a shape just short of a hat-shaped steel sheet pile product (i.e., approximately the shape of a hat-shaped steel sheet pile product). The perforated roll 45 changes the angle between the portion corresponding to the flange of the finishing material 19a (i.e., the flange-corresponding portion) and the portion corresponding to the web of the finishing material 19a (i.e., the web-corresponding portion), as well as the angle between the portion corresponding to the arm of the finishing material 19a (i.e., the arm-corresponding portion), thereby bending and forming the height and width of the finishing material 19a into a predetermined shape (i.e., a cross-sectional shape similar to the product). In particular, when manufacturing hat-shaped steel sheet piles, the method used is to roll the rolled material (rough material to finished material 19a) to a low height in the roughing mill 10 to the finishing mill 19, and then bend the rolled material in the bending machine 20 to raise its height to the desired product height. This makes it possible to manufacture large-sized hat-shaped steel sheet pile products.

Also, as shown in FIG. 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 perforated mold 55. This perforated mold 55 has a shape similar to the desired product shape, and changes the angle between the portion corresponding to the flange formed in the first stand 22 of the bending machine 20 (i.e., the flange-corresponding portion) and the portion corresponding to the web of the finishing material 19a (i.e., the web-corresponding portion), as well as the angle between the portion corresponding to the arm (i.e., the arm-corresponding portion), thereby forming the flange shape, arm shape, and joint shape into the desired shape (i.e., the product shape). In other words, in this second stand 23, the inclination angle of the flange-corresponding portion, which was insufficient for the product shape when formed in the first stand 22, is changed to an angle appropriate for the product shape.

Here, the roll gaps in the grooved dies 45 and 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. In other words, the bending machine 20 does not reduce the thickness of the finishing material 19a, 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, as described below, to perform bending.

In this specification, "contact" refers to a state in which only one of the upper or lower surfaces of a specific portion of the finishing material 19a abuts against the peripheral surface of a 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.

For example, the roll gap at the portions facing the web corresponding portion and the flange corresponding portion is preferably approximately 0.5 mm to 3 mm larger than the thickness of the flange corresponding portion and the web corresponding portion of the finishing material 19a. Additionally, at the portions of the grooves 45 and 55 that overlap the arm corresponding portion of the finishing material 19a, the roll gap may be configured to be larger than the thickness of the arm corresponding portion over the entire cross section. If the roll gap allowance range is smaller than 0.5 mm, there is a possibility that the thickness will be reduced due to variations in the thickness of the finishing material 19a, increasing the load on the bending machine 20. If it is larger than 3 mm, there is a possibility that the inclination angle of the flange corresponding portion cannot be formed to the target angle.

<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 change in shape 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. As shown in Figure 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. In addition, the finishing material 19a has a thickness that 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 product joint.

The finishing material 19a shown in Figure 6(a) is bent in the groove 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). In other words, in the first stand 22, bending is performed so that the height of the finishing material 19a becomes large.

Next, as shown in Figure 6(c), in the groove 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 (to the angle _α2 shown in Figure 6(c)), and the finishing material 19a is bent into approximately the shape of the product.

Figure 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 a contact point. In Figure 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 specified points, 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 Figure 7(a). Here, "contact" means that at least the material and the grooved rolls are in contact, and may also mean that a force pressing against the material is applied.

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. Meanwhile, 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, a reaction force is generated in a direction that balances the reaction force at 70a and 70b, respectively. This allows corner portions 70 and 71 to undergo plastic deformation.

Here, by contacting the central portion 60a of the underside (outside) of the web corresponding portion 60 shown in Figure 7(b) with the opposing pre-perforated rolls 41, 51, the corners formed by the flange corresponding portions 62, 63 and the web corresponding portion 60 can be efficiently bent. During bending, the web corresponding portion 60 tends to warp downward in the figure, so by contacting the pre-perforated rolls 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 to keep the arm corresponding portions 65, 66 approximately horizontal.

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

Furthermore, as shown in Figure 7(d), in addition to the locations described in Figures 7(a) to (c) above, the upper surfaces (outer surfaces) 68a, 69a of the joint corresponding portions 68, 69 may be brought into contact with the upper caliper 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 even more accurate bending.

Note that while suitable contact points with the finishing material 19a during bending have been described with reference to Figures 7(a) to (d), as shown in Figure 7, the respective contact points during bending are not positioned and configured to reduce the thickness of the finishing material 19a. Specifically, the configuration does not allow a specific point of the finishing material 19a to be pressed from both sides by both the upper and lower slotted rolls (i.e., reduced), and the roll gap between the upper and lower slotted 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 pressed down, there is no need to unnecessarily increase the reduction reaction force.

Furthermore, Figure 7 illustrates and describes 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 Figure 7, additional contact points may be provided.

<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 and (bending) amount of the rolled material (finished material 19a) increase. In particular, when bending is performed using multiple stands (e.g., the first stand 22 and the 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).

In this specification, "flange width" refers to the width of the flange corresponding portions 62, 63 of the rolled material (finished material 19a), and the length along the flange corresponding portions 62, 63. Specifically, as shown in Figure 8, on a line (dashed line in Figure 8) passing through the thickness centers of the web corresponding portion 60, flange corresponding portions 62, 63, and arm corresponding portions 65, 66, the flange width B is defined as the linear 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. Because this length is approximately the same as the flange width length of the final product, it may also be defined as the flange width length of the final product.

Figure 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 using 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 Figure 9 represents "tandem torque/single torque" and the horizontal axis represents "stand distance L (m)."

As shown in Figure 9, at the first stand 22, the value of "tandem torque/solo 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 tends to decrease as the stand-to-stand distance L becomes larger. As the stand-to-stand distance L increases, the torque converges almost to the solo torque.

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 greater 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 is performed in tandem is roughly equal to the torque when bending is performed by the second stand alone.

Therefore, further study was conducted on hat-shaped steel sheet piles with different cross-sectional dimensions. Here, for example, if the forming torque of the rear stand (second stand 23) is 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, but in that case the forming torque of the front stand would become excessive. Therefore, the inventors studied conditions under which the distribution of bending angles and the inter-stand distance L would be appropriate and the forming torque of the front and rear stands would be balanced.

Even in the case of hat-shaped steel sheet piles with different cross-sectional dimensions, the same relationship as described above is obtained between the inter-stand distance L and the forming torque of the rear stand. In other words, it has been revealed 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.

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

<Relationship between forming torque and stand distance>
As described above, the inventors have considered that the forming torque in the rear stand of a bending machine 20 consisting of two stands 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 suitable relationship and suitable 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.

The inventors defined the minimum value of the forming torque of the downstream 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 downstream 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 rolling 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.

As shown in Figure 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 motor capacity 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 associated 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 value less than 1.5 relative to the minimum torque is within an acceptable range in terms of equipment costs and power consumption. Figure 10 shows that when the torque ratio is kept at 1.4 or less, the L/(B/1000) value in the bending machine 20 satisfies the following equation (1):
4.4≦L/(B/1000)...(1)

Furthermore, from the viewpoint of further reducing equipment costs and power consumption in bending, it is preferable to keep the torque ratio 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)

On the other hand, as shown in FIG. 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 FIG. 9 ), so the torque ratio remains at 1. Increasing the inter-stand distance L increases the size of guide equipment for guiding the rolled material between the stands, which raises concerns about increased equipment costs. Furthermore, the stability of the material passing through the stands may also be impaired. For these reasons, it is not advisable to increase the inter-stand distance L more than necessary. As shown in FIG. 10 , when the value of L/(B/1000) is 7.0 or more, 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 formula (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)

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-shaped steel sheet pile products with a flange width of less than 377 mm are manufactured using the equipment and method of 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 approximately half that. In other words, the technology of the present invention can be effectively applied when manufacturing hat-shaped steel sheet piles with a flange width of 377 mm or more. Furthermore, when manufacturing hat-shaped steel sheet piles with a flange width of 500 mm or more, the forming torque is large, and an increase in this forming torque has a significant impact on the equipment, so the application of the technology of the present invention is particularly effective.

<Action and effect>
9 and 10, in manufacturing a hat-shaped steel sheet pile 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 tendency as for the torque is observed for the load, the load of the second stand 23, which is the rear stand, can also be reduced. As a result, the motor capacity as the equipment driving force can be minimized, and the motor and ancillary equipment can be made smaller, thereby reducing equipment costs, saving space, and suppressing power consumption.

In other words, by bending the rolled material in the hot state after hot finish rolling, it is possible to improve the efficiency and productivity of the equipment when manufacturing large products such as hat-shaped steel sheet piles. Note that "hot" here refers to the temperature at which the transformation of the rolled material is complete after hot rolling.

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 is possible to manufacture hat-shaped steel sheet piles of multiple sizes with a forming torque that fits within the equipment specifications of the same bending machine.

As mentioned above, bending is performed in a hot state. It is preferable to arrange the finishing rolling mill 19 and the bending machine 20 in tandem and perform 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 subsequent stand is minimized, the temperature at the crop portion (unsteady portion) at the tip of the rolled material may drop, causing misalignment and jamming. Therefore, the forming torque tends to increase momentarily 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.

The above describes one example of an embodiment of the present invention, but the present invention is not limited to the illustrated form. It is clear that a person skilled in the art can conceive of various modifications and alterations within the scope of the ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

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 the conditions (conditions defined by formula (1) or formula (4)) described in the above embodiment for each of two adjacent stands.

The number of stands is determined by balancing 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-compatible 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-compatible portion during rolling decreases, and the total required bending angle tends to increase. While it is generally preferable to ensure that the motor capacity is equal to each stand's torque, the bending angle at the first stand 22 is also limited by conditions 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.

In addition, in the above embodiment, the upper and lower perforated rolls of the bending machine 20 can also be configured so that only one of the upper and lower perforated rolls is driven, and the other is not. By configuring the bending machine 20 so that only one of the upper and lower perforated rolls is driven, it becomes easier to balance the speed of the sheet metal when bending is performed in tandem using multiple stands. This reduces the generation of tension in the rolled material due to speed imbalances between multiple stands, stabilizes the sheet metal passing, and prevents unnecessary deformation of the rolled material. In addition, the drive mechanisms, such as the motor, spindle, and gears required to drive the rolls, can be simplified, resulting in smaller equipment and reduced equipment 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 positions shown in Figures 3 to 5).

In addition, the above embodiments and their variations have been described with examples of hat-shaped steel sheet pile products being 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 manufacturing in the opposite downward-opening position (with the arm-corresponding portion below the web-corresponding portion).

In the steel sheet pile manufacturing equipment of the present invention, following hot finish rolling, flange bending was performed using a bending machine consisting of two consecutive stands to produce 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-to-stand distance L was varied within the range of 1.8 m to 4.8 m. The torque and torque increase ratio under these conditions are shown in Table 1 below.

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 defined 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.

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. In other words, because Examples 1 to 5 satisfy the conditions defined by the above formula (1) or (4), the torque of the subsequent stands is suppressed. This allows, for example, for the equipment to be downsized and for power consumption to be reduced.

The present invention can be applied to manufacturing equipment and methods for hat-shaped steel sheet piles.

DESCRIPTION OF SYMBOLS 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... First stand 23... Second stand 40... Upper groove type roll 41... Lower groove type roll 44... Housing 45... Groove 50... Upper groove type roll 51... Lower groove type roll 54... Housing 55... Groove 60... Web corresponding part 62, 63... Flange corresponding part 65, 66... Arm corresponding part 68, 69... Joint corresponding part 70, 71... Corner part T... Rolling line

Claims (6)

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. 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. The manufacturing facility for hat-shaped steel sheet piles according to claim 1, wherein in the plurality of stands constituting the bending machine, only one of the upper and lower slotted rolls of each stand is driven. The manufacturing facility for a hat-shaped steel sheet pile according to any one of claims 1 to 3, characterized in that the bending machine and the finishing rolling mill are arranged in tandem. The manufacturing facility for a hat-shaped steel sheet pile according to any one of claims 1 to 4, characterized in that a flange width of the hat-shaped steel sheet pile is 377 (mm) or more. A manufacturing method for manufacturing a hat-shaped steel sheet pile in the manufacturing equipment of any one of claims 1 to 5,
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.