EP1338351B1

EP1338351B1 - Method of correcting U-shaped sheet pile

Info

Publication number: EP1338351B1
Application number: EP03002697A
Authority: EP
Inventors: Toru Yuasa; Hiroshi Shikano
Original assignee: Sumitomo Metal Industries Ltd
Current assignee: Nippon Steel Corp
Priority date: 1995-09-29
Filing date: 1996-09-18
Publication date: 2011-04-27
Anticipated expiration: 2016-09-18
Also published as: AU7000396A; CN1165489A; TW346422B; DE69630670D1; EP1338351A1; KR980700137A; CN1159120C; DE69630670T2; CN1313152A; EP0795364A1; DE69638361D1; EP0795364A4; AU692404B2; EP0795364B1; KR100480243B1; CN1073893C; WO1997012701A1

Description

(Technical Field)

The present invention relates to a method of reforming U-shaped steel piles for use in civil engineering and building construction, and particularly to a method of reforming U-shaped steel sheet piles having an arm portion between a flange and a joint.

(Background Art)

Steel sheet piles are shaped by hot rolling and are cut to a predetermined length. While the cooling is taking place, warping or bending occurs in the longitudinal direction due to formation of internal stresses.
"Warping" means a large curve or edge curve in the direction perpendicular to the sheet pile wall 2 of a U-shaped steel sheet pile as illustrated by symbol "C" in Figure 1, and "bending" means a large curve or edge curve in the direction parallel to the sheet pile wall 2 of a U-shaped steel sheet pile as illustrated by symbol "B" in Figure 2. According to JIS A 5528, the tolerance for bending of U-shaped steel sheet piles is defined as being smaller than the length X 0.12% for steel sheet piles having a length of 10 m or less, and as being smaller than (length - 10 m) X 0.10% + 12 mm for steel sheet piles having a length over 10 m. The tolerance for warping of U-shaped steel sheet piles is defined as being smaller than the length X 0.25% for steel sheet piles having a length of 10 m or less, and as being smaller than (length - 10 m) x 0.20% + 25 mm for steel sheet piles having a length over 10 m.
Correction of these malformations is usually carried out using a roller straightener. However, since a straightener has, for example, four upper rollers and three lower rollers positioned in a zigzag arrangement, a satisfactory level of correction cannot be achieved for the front and rear ends of a pile. Especially, it is rather difficult to reform the bending and warping at the front and rear ends of a pile with a roller straightener, and it is general to reform the bending and warping at the front and rear ends with a press reformer after correction with a roller reformer.
Figure 3 illustrates correction of bending with a press reformer for a U-shaped steel sheet pile 1 to be reformed. In the illustrated case, a press rod (not shown) is provided to apply a pressing force in the direction shown by an arrow through a jig 5. On the opposite sides of the pile 1, jigs 6, 8 which support outer surface 4 of the flange of the U-shaped steel sheet pile 1 are provided to restrict movement of the pile.
However, in the case of a U-shaped steel sheet pile which possesses high ridigity against bending in the longitudinal direction, as shown in Figure 4a and figure 4b, respectively, correction of bending cannot be achieved even if the outer surface 4 on the one side (see Figure 3) is pressed, but deformation of a sectional shape occurs such that the width of the pile to be reformed is narrowed from the standard width W_o to the width W₁ shown by dashed lines. Furthermore, there occurs the problem that recesses D shown in Figure 4b are formed on the flange portions. These problems frequently occur when correction of bending is carried out for U-shaped steel piles having an arm portion between a flange and a jount.
There have been some proposals for correction of warping of U-shaped steel sheet piles. Japanese Patent Application Laid-Open Specification No. 61-63316 , for example, discloses a roller straightener comprising a pair of upper and lower rollers having a correcting section with which a web portion and flange portions of U-shaped steel sheet piles are grasped. The roller straightener comprises a joint restricting section provided next to both sides of the correcting section of the upper roller, which restricts the joint portion of the U-shaped steel sheet pile. Japanese Patent Application Laid-Open Specification No. 55-70418 proposes a similar arrangement.
As shown in Figur 5, for example, straightening rollers 10 of U-shaped steel sheet piles are designed such that a web 12, flanges 14, and joints 16 are respectively restricted on their outer surfaces by a straightening roller 10a, 10b, and a roller 18, each separated from each other, so as to achieve correction by repeating bending in longitudinal and transverse directions, and such that the width of a pile can be adjusted by rollers 18 which restrict the outer surfaces of the joint 16. As mentioned before, since correction is performed while restricting the web and flanges, malformation can be corrected without deformation of the sectional shape.
However, as shown in Figure 6, for U-shaped steel sheet piles having an arm 19 between a joint 16 and flange 14, the angle between the flange and the joint differs from a target one for a final product.

(Disclosure of the Invention)

An object of the present invention is to provide a roller straightening method, which can achieve correction of warping without deformation of a sectional shape for U-shaped steel sheet piles having an arm portion.
The inventors studied the problem that the angle between a flange and a joint differs from that of the final product when warping is correctd using rollers for U-shaped steel sheet piles having an arm portion. The inventors completed the present invention based on the finding that it is not enough to merely rstrict the full surfaces of the web and flanges, but that the correction of such an arm portion can be achieved precisely by means of restricting not only the web and flange, but also an arm portion with their full surfaces, and preferably by using a roller straightener having integrated upper and lower rollers.
The present invention is a method of correcting malformation of U-shaped stell sheet piles comprising a web portion, flange portions, and joint portions, and an arm portion between the flange portion and the joint portion, characterized by using a roller straightener by which not only the web and flange portions, but also the arm portion are restricted from the lower and upper sides thereof, and preferably by using a roller straightener having integrated upper and lower rollers.
In a preferred embodiment of the present invention, when the arm portion between the flange and joint portions is restricted, a straightening roller may be used to restrict the arm portion from the lower and upper side of the arm portion at an angle different from that required for a final product.
Thus, according to the roller straightening method of the present invention, straightening rollers which can achieve correction of malformation of U-shaped steel sheet piles by repeating bending in transverse and longitudinal directions comprises rollers restricting the upper side of the pile and rollers restricting the lower side of the pile, the upper and lower rollers being positioned in a zigzag arrangement.

(Brief Description of Drawings)

Figure 1 is a diagrammatic illustration of warping of steel sheet piles.
Figure 2 is a diagrammatic illustration of bending of steel sheet piles.
Figure 3 is a schematic view showing press correcting of bending of steel sheet piles.
Figure 4a illustrates a way of reducing the width of steel sheet piles by press straightening, and Figure 4b illustrates formation of local recesses in the surface of a flange.
Figure 5 is an illustration of conventional roller straightening for U-shaped steel sheet piles.
Figure 6 is an illustration of conventional roller straightening for U-shaped steel sheet piles having an arm portion.
Figure 7 is an illustraion of an arrangement of correcting rollers and a U-shaped steel sheet having arms in accordance with the present invention.
Figures 8a and 8b are illustrations of upper and lower straightening rollers, respectively, for U-shaped steel sheet piles having arms in accordance with the present invention.
Figure 9 is an illustraion of a section of a U-shaped steel sheet pile while correction is carried out with an upper roller.
Figure 10 is an illustration of a section of a U-shaped steel sheet pile while correction is carried out with a lower roller.
Figure 11 is a graph showing variation of an angle between an arm and a flange with respect to the longitudinal distance.
Figure 12 is a graph showing variation of width with respect to the longitudinal distance.
Figure 13 is a graph showing variation of an angle between an arm and a flange with respect to the longitudinal distance.
Figure 14 is a graph showing variation of width with respect to the longitudinal distance.

(Best Mode for Carrying Out the Invention)

Figure 7 is an illustration of an arrangement of straightening rollers for U-shaped steel sheet piles having arms, as an example of a straightening roller of the present invention. In the drawings, a U-shaped steel sheet pile comprising a web 30, flanges 32, an arm 34, and joints 35 is restricted by upper rollers 36, 36, and lower rollers 38, 38 together with outer rollers 40 with respect to the web and flanges as well as the arms. In the illustrated embodiment, the upper and lower straightening rollers 36, 38 each have a one-piece construction so as to enable the web 30 and flanges 32 to be restricted with the same rollers.
When the angle between an arm 34 and a flange 32 before correction is different from that of a final product, each roller 36, 38 is provided with a tapered portion which restricts the arm 34, and correction by repeated bending can be carried out to correct the angle to be the same as that of the final product.
Figures 8a and 8b schematically show an example of such straightening rollers of the present invention. Compared with the case shown in Figure 7, it is noted that the rollers 36, 38 are provides with a tapered portion having an angle α.
In both cases, straightening rollers are used to restrict not only a web and flanges but also arms from above and below. Especially, in the case shown in Figures 8a and 8b, when an arm portion between flange and joint portions is restricted, straightening rollers are employed to restrict the arm from above and below at an angle different from that of the product.
It is to be noted that in the illustration the upper and lower rollers 36, 38 are shown as being positioned such that the roller axes are aligned in the same vertical plane, but in fact they are arranged in a zigzag pattern.
A method by which the roller straightening can be achieved efficiently by restricting the arm portion as described above will next be described.
Straightening by repeated bending is performed with the upper and lower rollers positioned in a zigzag form and contacting the pile at three points. An example will be described in which a correcting force is applied from the upper roller and the force is received by the lower rollers. In this case, as shown in Figure 9, if the arm 34 is not restricted, the angle between the arm 34 and the flange 32 decreases. Namely, the arm is deformed in such a way that an upstand angle θ of the arm 34 increases upwardly. In the drawing, the arm 34 is deformed in the direction shown by arrows. In contrast, if the arm 34 is restricted from above as well as from below in accordance with the present invention, the section of the U-shaped steel sheet pile can be maintained without occurrence of deformation.
In addition, when a correcting force is applied by the lower roller and the force is received by the upper rollers, as shown in Figure 10, if the arm 34 is not restricted, the angle between the arm 34 and the flange 36 increases. Namely, the arm is deformed in such a way that an upstand angle θ of the arm 34 increases downwardly. In the drawing, the arm 34 is deformed in the direction shown by arrows. In contrast, if the arm 34 is restricted in accordance with the present invention, the section of the U-shaped steel sheet pile can be maintained without occurrence of deformation.
Thus, according to the present invention, since arm portions together with web and flange portions are restricted, and preferably the web and flange portions are restricted by the same rollers from above and below, it is possible to achieve straightening without damage to the cross-sectional shape of a final product, as illustrated in Figures 9 and 10. Especially, when all portions other than the joint portions are restricted by the roller grooves, it is possible to efficiently correct not only warping in a vertical direction but also slight bending in a longitudinal direction.
According to the present invention, therefore, even for U-shaped steel sheet piles having arm portions and exhibiting high stiffness against bending and warping, compared with U-shaped piles without arms, it is easy to remove slight bending in a longitudinal direction as well as warping in a vertical direction by means of pressing correction or rolling correction and the arm portion can be maintained at a desired angle.
Effects of the present invention will be explained in detail with reference to the following working examples.

(Example 1)

In this example, roller correction according to the present invention was applied to U-shaped steel sheet piles having an arm between joint and flange portions.
The dimensions of sheet piles to be reformed are shown in Table 1.

Width 640 mm

Arm 90 mm

Warping 10mm/15.3 m

Length 15.300 mm

Specification SY295 (JIS)

Note : Number of piles : 20
For comparison, conventional straightening rollers were used to restrict only a web and flanges separately, as shown in Figure 6. According to the present invention, however, a web and flanges were simultaneously restricted by the same rollers, i.e., by one-piece rollers, as shown in Figure 7, and an arm was also restricted by the same lower and upper rollers. The section of the pile after correction of bending was examined for the conventional method and the present invention method.
When straightening rollers of the present invention were used, warping in the longitudinal direction was completely removed, and the sectional shape of the arm and the width remained substantially unchanged.
When a web, flanges, and an arm were separately restricted by different upper rollers in accordance with an embodiment of the present invention, since it is impossible to restrict a border area between the web and the flange as well as a border area between the flange and the arm with rollers, correction of warping with such separate rollers was not adequate.
Fiure 11 shows variation of the angle between a flange and an arm with respect to longitudinal distance, and Figure 12 shows variation of width with respect to longitudinal distance.
Figure 11 is a graph obtained by plotting variation (Δθ, degree) of an angle (θ) of an arm before and after correction with respect to longitudinal distance (L₀) of a U-shaped steel sheet pile. As is apparent from the graph, in the case of the present invention indicated by the symbol •, variation was substantially constant regardless of the longitudinal distance. In contrast, in the conventional case indicated by the symbol 0, the arm was bent downwardly. Depending on the amount of reduction or a reduction pattern during correction, the arm was bent upwardly or downwardly in conventional methods (0), but the tendency of deformation was the same as in this case.
Figure 12 is a graph obtained by plotting variation (ΔW₀) in width (W₀) before and after correction with respect to longitudinal distance (L₀) of a U-shaped steel sheet pile. In the drawings, examples of the present invention are indicated by the symbol •, and examples of the conventional method are indicated by the symbol 0. In the case of the present invention, there was substantially no variation.
Thus, according to the present invention, compared with the conventional method the angle between flange portions and arm portion as well as the width remained unchanged, with good results.

(Example 2)

In this example, in the same manner as in Example 1, the straightening rollers shown in Figure 7, and straightening rollers having tapered portions shown in Figure 8 (taper angle is 3°) were used to determine whether differences were found with respect to sectional shape after correction of bending.
In either case, warping in the longitudinal direction was successfully removed.
Figure 13 shows variation (Δθ) of the angle (θ) of an arm before and after correction with respect to longitudinal distance (L₀), and Figure 14 shows variation (ΔW₀) of the width (W₀) before and after correction with respect to longitudinal distance (L₀). In the drawings, the symbol • indicates the case in which a tapered portion was not provided, and the symbol "+" indicates the case in which rollers with tapered portions were employed. Depending on the amount of reduction or a reduction pattern during correction, the arm was bent upwardly or downwardly in the case in which the tapered portion was not provided (•), but the tendency of deformation was the same as in this case.
It is noted from these results shown therein that provision of a tapered portion has an effect to reduce the variation both of an angle of arm and of width.

(Industrail Applicability)

As is apparent from the above working examples, employing pressing correction and correction jigs of the present invention, it is possible to achieve correction of U-shaped steel sheet piles efficiently in a short time.
Correctiong rollers of the present invention can be used to achieve roller correction of U-shaped steel sheet piles having an arm portion without changes in the sectional shape of the pile, i.e., the width size and the angle between arm and flange portions. Thus, the present invention has a marked effectiveness from an industrial point.

Claims

A method of roller straightening U-shaped steel sheet piles (1) comprising a web portion (30), flange portions (32), and joint portions (35), and an arm portion (34), between the flange portion (32) and the joint portion (35), characterized by using a roller straightener by which not only the web (30) and flange portions (32), but also the arm portion (34) are restricted from the lower and upper sides thereof.
A method of roller straightening U-shaped steel sheet piles as set forth in claim 1, wherein said roller straightener which restricts a web portion (30), flange portions (32) and arm portions (34) from the lower and upper sides thereof comprises an intergrated upper roller (36) and an integrated lower roller (38).
A method of roller straightening U-shaped steel sheet piles as set forth in claim 1, wherein said roller straightener comprises upper (36) and lower rollers (38) which are positioned in a zigzag form in the upper and lower sides.
A method of roller straightening U-shaped steel sheet piles as set forth in claim 1, characterized in that, when the arm portion (34) between the flange (32) and joint portions (35) is restricted, a straightening roller is used to restrict the arm portion (34) from the lower and upper sides of the arm portion (34) at an angle different from that required for a final product.
A method of roller straightening U-shaped steel sheet piles as set forth in claim 4, characterized in that said straightening rollers (36, 38), restricting the web (30) and flange portions (32) as well as the arm portions (34) from the upper and lower sides comprise an integrated upper roller (36) and an integrated lower roller (38).
A method of roller straightening U-shaped steel sheet piles as set forth in claim 4, wherein said roller straightener comprises upper and lower rollers (36, 38) which are positioned in a zigzag from in the upper and lower sides.